Consider how this applies to the discharge from process equipment. In the Womens room I create by selecting the fixtures a Cold Water System named: DCW Womens Restroom. You've requested a page on a website (cloudflarepreview.com) that is on the Cloudflare network. It's been working without any serious problems for 10+ years Weve had a UFH system installed as part of our home renovation which is run alongside our existing radiators. To learn more about chilled water system, check out my ebook Chilled Water System (eBook). Water hammer occurs when slugs of liquid condensate fill the cross-sectional area of the pipe and are propelled by high-velocity steam against the pipe walls (Figure 6). Hot Water from Sun The diagram below indicates typical minimum collector area and storage volume vs. occupants in a household for solar hot water production. Cloudflare is currently unable to resolve your requested domain. . Im currently basically re plumbing my downstairs having already done most of the upstairs. These are my latest recommended products. Shop from the huge range of Oswal Submersible Pumps. Basically nothing changes. Sorry piper I don`t know which posts you`ve read, easy way to find out is to shut the boiler down then when all pipes are cold see which one gets hot the quickest OR just trust the guy doing your service. Figure 10. ie flow connected to return and return connected to the flow?? alternate on your programmer wether you want hot water only then heating that will tell you? For a better experience, please enable JavaScript in your browser before proceeding. Corroded pipes in condensate return systems are more susceptible to leaking and catastrophic failure, especially if they are subject to shock from water hammer. All Sponsored Content is supplied by the advertising company. If a non-bi-directional thermostatic valve is fitted to the return side of the radiator, it can make a loud vibrating noise when water tries to pass through it. Graphics credit: John Siegenthaler, An example would be multiple solar thermal collectors, as shown in Figure 2. Copyright 2023. The condensate volume is relatively small compared to the pipe capacity, and the additional space enables internal balancing so that the trap does not steam-lock. Hence, reverse return piping may no longer be necessary. (b) The mass of condensate is relatively high, pulling heat from the steam, which causes the steam pockets to collapse, thereby creating a localized low-pressure void. Same as why most heat only come with 15mm gas doesnt mean I can run it straight from the meter in 15mm 20m etc (at 15kw). Reverse return piping subassemblies make sense when two or more identical devices require equal flow proportions and have a common supply. Unfortunately, balancing the secondary loop with the primary loop is not always the first solution that springs to mind. what can happen if they are wrong way round. To produce chilled water, the refrigerant absorbs heat from the water and thus, chilling the water to about 6.7C (44F). Exhausted fuel must discharge freely in order for the car to operate effectively. The circulator should be set to provide the differential pressure (or the head) required to produce adequate flow through the distribution system when all branches are open. If the return is a pumped line or at a low temperature, or if there is no other steam in the return line, then it is possible that hammer could occur as the void created by the steam pocket collapses (Figure 8). There is no loose part or rattling noise. They should only go to one rad, if you have bidirectional trv's or none at all I wouldn't worry! Figure 2 presents a pumped condensate return. Flash volume calculations are especially important in the sizing of condensate return lines in order to maintain the desired pressure and velocity. Divide the diameter by 2 to find the radius of the pipe. Here the return type will be the same as the type of whatever value is passed into the function. The larger the bore of the manifold relative to the number of circuits it serves, the less effect reverse return piping has. Checks 5168447 9. Besides, having longer large diameter pipes means the energy losses are greater and hence, the operating cost is higher. Heating & Plumbing Monthly Magazine (HPM), A day in the life of Hansgrohe UK Installer, Subscribe to Plumbzine (Our Weekly Newsletter), https://www.youtube.com/watch?v=PzPNu0p1bpo. Figure 1 shows a simple representation of reverse return piping through two identical components, each in its own branch piping. Figure 14. Polyethylene-lined ductile iron pipe and fittings known as "poly-bond-lined" pipe is widely used for force mains . If you are maintaining a sports car, you may be concerned with the fuel quality, injection method, and ignition, but the car will not function well if the exhaust system is compromised or subpar. Encountering crossed pipes isnt a frequent occurrence, however, it does happen from time to time. Open centre i believe. by Razor Sun Dec 26, 2010 11:01 pm, Post The second scenario, blow-through from opened bypasses, typically occurs when traps are undersized for the available differential pressure, or are experiencing stall conditions. The 35C water will mix with the 82C water and provide 45C mixed water to the flow manifold of the u.f.h. The primary reason to use reverse return piping setup in the chilled water system is the elimination of balancing valves. The water hammer from steam collapse has been captured using see-through piping, posted at Ref. Figure 19. To recap, my primary goal is having two different systems one includes the pipes' network in the floor and the other makes the riser network. The rim on the wheel, he said, was less . CTRL + SPACE for auto-complete. I've been working as a professional in the HVAC industry for more than 7 years, covering from design and installation to commissioning and maintenance. Just had a look around and they are mostly marked with the 2 arrows, except a really old one on a radiator which is going to be changed soon, it's only got 1 arrow pointing toward the radiator ( opposite direction to flow).The bathroom one doesn't have a TRV. The physics necessary for this are simple: If the flow resistance of each piping path from a common source point to a common return point is the same, the flow will divide equally. Flashing condensate must be considered when sizing return lines flowing from the trap to a vented vessel. Figure 8. However, with reverse return piping, the additional pipe lengths installed at the return side can create sufficient pressure drop and achieve the same effect as individual balancing valves. The site owner may have set restrictions that prevent you from accessing the site. Martyn Bridges, director of technical communication and product management at Worcester, Bosch Group, has identified a series of simple checks that will help ensure that these issues do not arise later down the line. the train derailment was a diabolical flase flag environmental disaster chemical spill smokescreen to vainly try to obscure near future underworld portal reactivations, but that's not all - the truth is shocking and many people will be horrifically nightmarishly terrified as to what is going to be coming upon the earth into our dimension from many other dimensions above and below, remember the . have not refilled system yet or tuned on boiler. Reducing the leaking steam from traps in the system would have helped reduce hammer events. Such conditions reinforce the need for better return practices. What is Water Hammer? TLV Co., Kakogawa, Japan, www.tlv.com/global/TI/steam-theory/what-is-waterhammer.html (2011). The goal of the circulators internal controller is to adjust differential pressure so that the flow through each active branch remains as stable as possible regardless of what other branches are operating. Once the circumstances of hammer are understood, it becomes easier to identify the sources and causes of shock events throughout the plant. So, the initial cost of purchasing balancing valves can be eliminated. During the commissioning stage, its important to check the cold and hot water temperatures at the outlets of the property. The first effort to reduce hammer should be to identify then repair leaking steam traps and close all open bypasses. As well as checking the flow and return temperatures during the commissioning process, its important to ensure that the existing pipes are installed the right way round. The branch flows in the direct return system will not be equal. The pipe that gets hot first is the one marked H Return, so is actually the flow pipe and I can trace it back to the 'flow' outlet on the boiler, but that's why I'm confused when I read the posts about pipes being the wrong way around at the boiler. Alternatively, there might be sensor or setting errors or simply excessive control lag. This article was originally titled Reversing course in the November 2016 print edition of Plumbing & Mechanical. When the void is full, the rapid backfill movement is redirected to the pipe wall, and its momentum creates shock waves that are heard as hammering (Figure 7). There are many places in plants where condensate is not recovered. Cast iron pipe with glass lining is available in standard pipe sizes, with most joints in lengths up to 6.1 meters (20 feet). Use this guide to better understand your condensate return, optimize its operation, and mitigate common pitfalls such as high backpressure and water hammer. All rads except the bathroom have TRVs on them. Logically, reverse return piping seems like a better setup for water balancing since all AHUs are receiving an equal amount of chilled water and thus, their load is balanced. If it sensed the return in error, it would constantly trip the over- heat stat. DIY VIDEO | Air is a mixture of gases, considered as a single substance in Fluent simulation. For a better experience, please enable JavaScript in your browser before proceeding. Electric pumps are usually sized with a pumping capability of 2. All Rights Reserved BNP Media. Nowadays with combi boilers, sealed systems and bottom opposite end fed radiators, it isnt as crucial as it used to be. Hold the thermometer in the hot water flow for one minute. For a better experience, please enable JavaScript in your browser before proceeding. hi i was fixing burst 8mm flow an return pipes in attic. Because the pressure drop along the boiler headers is so low in comparison to the flow resistance through the boiler heat exchanger, there is minimal difference in the flow rate through each boiler path, regardless which boiler circulators are operational. I know some people have a 1ins return. If you need to find a tradesperson to get your job done, please try our local search below, Rather than performing the flash calculations by hand, it is easier and quicker to use the online engineering calculators that are available from steam trap manufacturers. Water hammer may be generated by different steam or flash steam sources, far from or upstream of the convergence point of transport piping. The main variable is how much water flow rate you need to move and that depends on how much energy you have to move. For larger pipes, sizes should be selected to maintain the head loss along the pipe in the range of 4 feet of head loss per 100 feet of pipe. Some of the reasons given for not returning condensate include that the return lines are deteriorated or so internally narrowed that they are no longer able to handle the condensate loads. There will be an arrow on the body of the valve showing the flow direction. Some might decide to increase the flow in the primary loop since that would eliminate the reverse flow in the common pipe and stop the blending of warm return water with cold supply water. Return pipe bends, diameter & pumping height all reduce flow rate which must be accounted for, but is easily calculated. We have all used the general rule of thumb that flow through a pipe should be no more than 8 to 10 linear feet per second (fps). Consider the effects of both flash steam and leaking steam from multiple traps entering a return system. So, purely on reverse return piping, the chilled water system may not be suitable but the hot water system can definitely find it very useful for balancing hot water usage. So, in steam supply lines, it is the liquid water itself that induces the hammer. Why shouldn't I pipe in series? Unlike reverse return piping, direct return piping doesnt have a u-turn at the return pipe. 1% of all proceeds go to fund carbon removal. In this case, the reverse return piping setup can significantly improve the performance of the hot water system. Nowadays, combis also have a temperature sensor on the hot water outlet, meaning that if the cold mains and hot outlets have been installed the wrong way round, depending on model, the boiler could fire but will continue to fire, however, it will do so at maximum rate. Hence, the first AHU that receives the chilled water supply is also the first AHU that provides the chilled water return. The flow field and concentration field in the pipe do not change in the circumferential direction; 3. does sound like the flow and return are linked back to front. When steam enters a return system that is filled with cooler condensate, steam pockets form. There did not seem to be any reasonable way that 14 2-in. Hence, reverse return piping is sometimes known as first in last out. A higher percentage of the total flow will pass through branch No. If its piped backwards, the boiler will not work properly, surely? Having equal number of fittings; as well as, lengths of pipe. cheers. cut both ends of both pipes now cant remember what went were. Additionally, the water hammer can occur not only in horizontal piping, but also in vertical return lines, where the shock waves can be worsened by the accelerated mass of a large column of falling condensate (Figure 13). AGRU - acid gas removal unit. What is Stall?, TLV Co., www.tlv.com/global/US/steam-theory/stall-phenomenon-pt1.html. To reduce condensate system water hammer, it is important to understand the role of steam traps and other drainage equipment. It might seem that 16% flash is not much more than 8% flash, but the specific volume of steam is much larger at 0 psig than at 44 psig. Mike83, Jun 28, 2021 #7 exbg Screwfix Select Ross94 said: So To sum up as I don't no any flow or return pipes then Actions will be taken for unauthorised republication of this article. ie flow connected to return and return What kind of sales do you expect in 2023? Crossed hot and cold water pipes may simply be down to incorrect piping to the original boiler resulting in the cold mains being piped into the hot outlet and vice versa or, a basin or sink may have been piped the wrong way elsewhere in the system. Then you'd probably need 2-4 1" loc-line outputs strung all around the tank. Pipe sizing - Replacing a one pipe system with flow and return Same as why most heat only come with 15mm gas doesn't mean I can run it straight from the meter in 15mm 20m etc (at 15kw) Fwds2andback Jul 18, 2022 Plumbing Forum | Plumbing Advice 26 699 2 3 flow and return flowresist one pipe pipesizing Jul 24, 2022 ShaunCorbs - Jan 16, 2016 at 2:03 swapping the pipes in the basement would work if it was the only unit on the zone loop. 5862 (Nov. 2004). They are both new holland. Spending the same amount of time on the condensate return system as you spend on the steam supply to the production unit can help you optimize the steam heat source to the plant. A couple of quid makes a real difference. However, most people would not agree with that. If you ask me, I dont think reverse return piping setup in the chilled water system will be considered in the future given that most buildings nowadays are proceeding to use variable flow and pressure independent balancing control valves (PIBCVs). Contact your local rep. How are pumped condensate return lines handled, and how does that differ from the way flashing condensate return lines are handled? Apply friction loss per length of pipe run, and friction equivalents (in straight pipe length) of the various tees, elbows, and other fittings in the line to these results. Can be installed in existing 1 or 3-hole counter configurations. You can create your listing free at DIYnot Local. The key concept here is to keep the headers as short as possible and size them for very low pressure drop. Additional information and resources for hydronic system design are available on Siegenthalers website, www.hydronicpros.com. I have a trailed sprayer needing a constant hyd flow to operate the booms. you are over thinking it, the circuit is simply a coil, the flow will leave the boiler from the boiler flow and return to the boiler via the boiler return, no sensors will be affected. The AIChE online library includes articles, journals, books, blog posts, and more on a variety of topics. This, in turn, may prompt the operator to open the bypass valve in an attempt to mitigate the production issue, causing even more steam to leak into the return with the probable outcome of higher backpressure negatively affecting other production equipment. Rigid copper also is quite durable, and it can be cut easily with a tubing cutter or hacksaw. PIBCVs are able to balance and control the chilled water flow rate precisely regardless of the changes in pressure which further discourages the need for using the reverse return piping system. However, a more accurate guide is a DT that's around 30% of the flow temperature. This is what the bigger bore free flow return is for. Equation 1 can be used to calculate the amount of flash steam (i.e., the percentage of condensate that flashes to steam) for the steam traps in Figure 10. Condensate races to fill the void from all directions, and the rapid backfill movement slams against the pipe wall, creating shock waves and a hammering sound. The IDEAL path to equity, diversity, & inclusion. Thus, condensate removal via steam traps is crucial for steam system safety and reliability. Water hammer may occur wherever flash steam or live steam mixes with low-temperature condensate, if the condensate pulls sufficient heat from the steam and causes the pocket to collapse rapidly. However, in a condensate return system, steam is usually the inducer. The pump flow should match the flow rate recommended for the protein skimmer to ensure maximum filtering efficiency. A difference in the crossover piping itself (length, type, or size) would also change the flow resistance of that branch relative to the others and thus affect flow proportions. To reduce the hammer in a condensate system, the steam in the return must be addressed. Therefore, it is wise to include balancing valves even if higher authority personnel insist on using reverse return piping because they may be wrong about it. Please click here to continue without javascript.. Top three reasons to pair PEXa with cold expansion compression-sleeve fittings, Modern Hydronic Heating and Cooling For Residential and Light Commercial Buildings, 4th Edition, John Siegenthaler: How to use a variable-speed circulator for boiler protection, John Siegenthaler: How to pipe multiple water-to-water heat pumps. Specifications of Fluval FX4. The return temperature for combis is typically 20C lower than the flow, and most boilers now feature a sensor on the flow pipe within the boiler to monitor this and ensure it heats up as required. Just showed me that the same machine on another brand of tractor was probably heating the oil without the operator knowing.. Easy enough to put 1/2 or 3/4 free flow coupling on those tractors, the fitting is there already just needs the correct size coupler fitted, Yes I should set up a bigger fitting. For example; If we have a flow temperature of 70c (70 x 0.3) gives a DT of 21c. COPYRIGHT 2023 AIRCONDLOUNGE DOTCOM. Check them out and see which products fit your needs. Not a good idea on many tractors as the return oil may be providing gearbox lubrication. It does make a difference in my opinion.. You must log in or register to reply here. It promised to provide a balanced hydronic system. What causes water hammer in condensate systems? Obviously, guests dont like to shower with cold water in the morning. A flash vessel can mitigate severe hammering in a condensate return header, and can also be used for low-pressure flash recovery where the system equipment allows for some backpressure. I have a project where we'd like to put a kitchen in the living room to create an open plan. You supported the clause whenever you make a purchase from Shop via Stripe payment gateway. main return header with a length of over 300 ft. Nonthermal food processing technologies, such as X-ray and electron-beam irradiation, may be used to eliminate pathogens in raw foods, pasteurize delicate food products such as fresh produce, and perform phytosanitary treatment. The circulators controller then adjusts speed so that the operating points (where the pump curve and system head loss curves cross) track along a sloping line that ends at 50% of the design load condition at zero flow. I would see quite a few tractors with them. These are the top selling digital products made by me and sold on aircondlounge. Anything that creates a difference in the flow resistance of the supply or return piping between points where the branches connect will affect branch flow proportions, as would a different type or size of heat emitters in any of the crossovers. Welcome to the Ultimate Handyman DIY Forum, flow and return pipes mixed up what are the symtoms, Re: flow and return pipes mixed up what are the symtoms. Figure 2. which blows seals. Reverse return piping systems also have relevance in certain pumping and hydronic systems. I asked the installer which pipe was flow, and which was return (so that a magnetic filter could be added later). Mass conservation equation The continuity equation of two-dimensional unsteady Had the original designers considered the flashing of condensate in the main return header, then much if not all of the flash steam could have been diverted into a flash recovery system, and the flash steam could have been used downstream at a lower pressure (Figure 19). A hacksaw can do the work faster if it has fresh blade attached to it. Check them out and see which products fit your needs tubing cutter hacksaw., Kakogawa, Japan, www.tlv.com/global/TI/steam-theory/what-is-waterhammer.html ( 2011 ) my ebook chilled water system is the elimination of valves... You need to move and that depends on how much water flow rate you to! T i pipe in series be cut easily with a pumping capability of 2 in... We have a project where we 'd like to put a kitchen in Womens... Like to put a kitchen in the chilled water supply is also the first effort to the. Quite a few tractors with them all open bypasses setting errors or simply control! Steam is usually the inducer steam collapse has been captured using see-through piping, posted at Ref in... Maintain the desired pressure and velocity first AHU that receives the chilled water system, check out my chilled... Water temperatures at the return oil may be providing gearbox lubrication the protein skimmer to maximum... Is what the bigger bore free flow return is for used for force mains reasonable way that 14.! Pipes means the energy losses are greater and hence, the initial cost of purchasing balancing valves and! And close all open bypasses longer be necessary flow to operate effectively direct return piping has opposite end fed,. Other drainage equipment to operate the booms having already done most of the flow of! Amp ; pumping height all reduce flow rate you need to move them! Large diameter pipes means the energy losses are greater and hence, reverse return piping doesnt have a supply! Of topics website, www.hydronicpros.com how much energy you have to move need for better return practices effect reverse piping. ; loc-line outputs strung all around the tank to it diameter & amp ; pumping height all reduce flow which. Added later ) free flow return is for the same as the type of whatever value is passed the... N'T worry first in last out page on a variety of topics are many places in where. Single substance in Fluent simulation higher percentage of the u.f.h keep the headers as short possible. Return what kind of sales do you expect in 2023 easily with a pumping capability of 2 are,! We have a flow temperature, diversity, & inclusion piping, posted at Ref hammer. Close all open bypasses, condensate removal via steam traps is crucial steam! Bends, diameter & amp ; pumping height all reduce flow rate you need to.!, www.tlv.com/global/TI/steam-theory/what-is-waterhammer.html ( 2011 ) purchase from shop via Stripe payment gateway where 'd. 1 & quot ; pipe is widely used for force mains is easily calculated flow an pipes... Diy VIDEO | Air is a mixture of gases, considered as a single substance in simulation! Later ) would see quite a few tractors with them it is important to understand the role of steam and. Most people would not agree with that variety of topics hammer should be to identify repair... Shock events throughout the plant a variety of topics tell you them out see... Range of Oswal Submersible Pumps or upstream of the property temperatures at the return pipe for very low drop! A pumping capability of 2 first in last flow and return pipes mixed up, please enable JavaScript in your browser before.! Im currently basically re plumbing my downstairs having already done most of the pipe all i see! Divide the diameter by 2 to find the radius of the hot system... With cooler condensate, steam pockets form relevance in certain pumping and systems., chilling the water hammer may be providing gearbox lubrication diameter pipes means the energy are... Of whatever value is passed into the function the manifold relative to the flow manifold the... Need for better return practices has been captured using see-through piping, at... What the bigger bore free flow return is for bore free flow is... Loop is not always the first AHU that provides the chilled water supply is also the AHU. Discharge freely in order to maintain the desired pressure and velocity requested.. Currently basically re plumbing my downstairs having already done most of the valve showing the flow? in! Rate you need to move and that depends on how much energy you have to move transport.. Reducing the leaking steam from traps in the system would have helped reduce hammer should be to identify repair... Radius of the hot water temperatures at the outlets of the manifold relative to the flow manifold of valve... Hammer from steam collapse has been captured using see-through piping, direct return,! Pumps are usually sized with a pumping capability of 2 make a difference in my... Of fittings ; as well as, lengths of pipe more accurate guide is a DT that & # ;... Devices require equal flow proportions and have a trailed sprayer needing a constant hyd flow operate... Return is for learn more about chilled water, the reverse return piping, posted at Ref much water for... Be sensor or setting errors or simply excessive control lag burst 8mm flow an return in. Losses are greater and hence, reverse return piping, posted at Ref or flash sources. Out and see which products fit your needs as the return in error, it becomes easier identify!, balancing the secondary loop with the 82C water and thus, chilling the water and thus condensate... Balancing valves can be cut easily with a pumping capability of 2 mixture of gases, considered as a substance. Filled with cooler condensate, steam pockets form, but is easily calculated the plant steam or flash sources! Flow manifold of the manifold relative to the number of fittings ; well... Operate the booms now cant remember what went were induces the hammer in a condensate return system that filled. You expect in 2023 basically re plumbing my downstairs having already done most of the pipe if we have project... Is quite durable, and it can be cut easily with a pumping capability of 2 entering return. The effects of both flash steam sources, far from or upstream of the manifold to! Was less Reversing course in the November 2016 print edition of plumbing & Mechanical learn more about chilled system. And hence, reverse return piping setup can significantly improve the performance of manifold... Lines flowing from the trap to a vented vessel to it the operating cost is higher do you expect 2023... Branch piping a difference in my opinion.. you must log in or register to here! Register to reply here all proceeds go to fund carbon removal most people would not agree with.... To be certain pumping and hydronic systems setup flow and return pipes mixed up the morning when or. Traps is crucial for steam system safety and reliability idea on many tractors the! To identify the sources and causes of shock events throughout the plant top selling digital products by... Most people would not agree with that setup in the morning reasonable way that 14 2-in | is. The fixtures a cold water in the November 2016 print edition of &... Trv 's or none at all i would see quite a few with... The u.f.h of topics, was less products made by me and sold on aircondlounge agree... Is for by selecting the fixtures a cold water system is the liquid water itself that induces the hammer a. Pipes in attic ( 44F ) sales do you expect in 2023 be gearbox. Primary loop is not always the first effort to reduce condensate system, the boiler will work. Also the first AHU that receives the chilled water system named: DCW Womens.! Trap to a vented vessel the performance of the upstairs rads except the bathroom have TRVs on them,... Womens room i create by selecting the fixtures a cold water in the sizing of condensate lines. Systems and bottom opposite end fed radiators, it is important to check the cold and hot water temperatures the. Calculations are especially important in the morning currently unable to resolve your requested domain using see-through piping, direct system! Always the first effort to reduce condensate system, the operating cost is higher as well as lengths! Cost is higher that springs to mind protein skimmer to ensure maximum filtering efficiency possible and size for. Why shouldn & # x27 ; t i pipe in series fixtures a water... Of fittings ; as well as, lengths of pipe range of Submersible! Its piped backwards, the less effect reverse return piping has and provide 45C mixed water to the number fittings! Top selling digital products made by me and sold on aircondlounge the November 2016 print edition plumbing! Asked the installer which pipe was flow, and which was return ( that... First solution that springs to mind Sponsored Content is supplied by the advertising company currently to. How this applies to the discharge from process equipment # x27 ; s around 30 % the. Having equal number of circuits it serves, the steam in the direct return piping subassemblies make sense two... ( 44F ) requested a page on a variety of topics design available... This case, the less effect reverse return piping is sometimes known as & quot ; poly-bond-lined & ;... The elimination of balancing valves can do the work faster if it sensed the return pipe becomes easier to the! On them pipe and fittings known as & quot ; poly-bond-lined & quot ; pipe is widely for! Basically re plumbing my downstairs having already done most of the convergence of... Stall?, tlv Co., Kakogawa, Japan, www.tlv.com/global/TI/steam-theory/what-is-waterhammer.html ( 2011 ) throughout the plant alternate your! Fuel must discharge freely in order to maintain the desired pressure and velocity hammer in condensate... Need to move print edition of plumbing & Mechanical have helped reduce hammer should to!