No check valve on HW return line - is this OK?

[Mitchell-DIY-Guy]

If you are going to use SharkBites or similar in your basement location my suggestion is treat them AS IF you were going to solder. That is, clean the pipe ends, and don't forget to buy the $10 tool to ream the ends properly and set the depth. Also, some of the push fittings have a sleeve. On some of them, the fitting is supplied OUTSIDE the fitting and they want you to use it if you are using the push fitting for PEX or other plastic tubing. In other cases the sleeve is kind of permanently inside the fitting for use with ALL tubing, and if you are not careful to ensure that the sleeve goes into the pipe, you can damage the fitting. I damaged at least one fitting with a little carelessness on the sleeve issue, and also learned quickly about the tool. If you don't feel comfortable soldering it's a good solution for your situation. I just used a simple brass swing check valve, nothing special, when I had to replace mine. Again, my system worked perfectly for 27 years. Some plumbers don't understand physics and think its impossible, but it was a plumber that installed mine in the first place. My supply pipes were ¾" copper and the return line was 1/2" copper.

I cannot speak to the problem of heat trap nipples but the if the pros don't like them, don't use them.

 

[Twowaxhack]

If you buy sharkbites and you don’t need the pipe stiffener, simply remove it by pulling it out with needle nose pliers.

 

[DIYQuestionGuy]

You’ll have to remove the heat trap nipple.

You’ll have to have enough head pressure to open the swing check.

If you don’t, you’ll need to drill a hole in the check to allow circulation and allow enough circulation to have a functional system that serves its intended purpose.

Drill the hole too small and it won’t work, drill the hole too large and you’ll get reversed flow.

It’s a dance, just like I said in an earlier post. It has to be customized in SOME cases. They all can be different.

Got it. Thanks! Did you happen to see the pic in my last post? How do I know if I need to remove the heat trap nipple or whether it's already been removed? Is the heat trap nipple the silver nipple first coming out of top of water heater the copper line is connected to?

Hate to question you, I do value your help, but wondering if you might be able to explain why this would need to be removed. Clearly hot water is flowing with this in place. Why does it need to be removed in my case? Just seeking to understand. I'm assuming it's because the return pressure in gravity loop is so low that it doesn't allow the hot water to flow from hot water heater outlet efficiently or something?? I'm just guessing. Appreciate your explanation.

 

[DIYQuestionGuy]

If you are going to use SharkBites or similar in your basement location my suggestion is treat them AS IF you were going to solder. That is, clean the pipe ends, and don't forget to buy the $10 tool to ream the ends properly and set the depth. Also, some of the push fittings have a sleeve. On some of them, the fitting is supplied OUTSIDE the fitting and they want you to use it if you are using the push fitting for PEX or other plastic tubing. In other cases the sleeve is kind of permanently inside the fitting for use with ALL tubing, and if you are not careful to ensure that the sleeve goes into the pipe, you can damage the fitting. I damaged at least one fitting with a little carelessness on the sleeve issue, and also learned quickly about the tool. If you don't feel comfortable soldering it's a good solution for your situation. I just used a simple brass swing check valve, nothing special, when I had to replace mine. Again, my system worked perfectly for 27 years. Some plumbers don't understand physics and think its impossible, but it was a plumber that installed mine in the first place. My supply pipes were ¾" copper and the return line was 1/2" copper.

I cannot speak to the problem of heat trap nipples but the if the pros don't like them, don't use them.

Thanks for shark bite tips. I hear you about prepping the pipe ends. I've used shark bites before (albeit with pex) and have the tools for prepping/cutting the pipes. I may give soldering a try. Been wanting to try that and this seems like low risk time to learn. It will likely come down to what supplies are available at the big box store and cost. Given the copper line is already in place a shark bite slip end and connection for swing valve may be most convenient for inserting valve in line if that makes sense.

 

[MicEd69]

While technically a swing check may indeed have some measurable cracking pressure, I don't think you'll find a cracking pressure rating on a swing check.

Twowaxhack is correct when he says, "All check valves have a cracking pressure."

But the thing about a rudimentary swing check valve like you have is that the cracking pressure all depends on the geometry of the valve and the angle of the installation. If the valve's geometry is such that the hinge point of the disc is offset from the center of gravity of the disk by 10 degrees, the cracking pressure would be that required to lift the weight of the disk a hair over 10 degrees.

I don't know what the weight of a swing check disc weighs, so let's assume it weighs twice that of a nickel, 0.176 oz or 0.011 lbs. The I.D. of a 1/2" copper pipe has an area of ~0.233 sq. in. The sin of 10 degrees is a bit under 0.174. So, with these assumptions the cracking pressure of a 1/2" swing check valve would be (0.011/0.233) x 0.174 = 0.0082 psi.

But some of my assumption may be off, so using a safety factor of 10, I would say the cracking pressure of a rudimentary 1/2" swing check valve would be something like 0.082 psi.

 

[Twowaxhack]

The cracking pressure of some swing checks have been enough that a gravity return would not operate. That’s when you start experimenting with drilling a hole in the check.

We can put that in our slide rule and smoke it.

 

[DIYQuestionGuy]

Twowaxhack is correct when he says, "All check valves have a cracking pressure."

But the thing about a rudimentary swing check valve like you have is that the cracking pressure all depends on the geometry of the valve and the angle of the installation. If the valve's geometry is such that the hinge point of the disc is offset from the center of gravity of the disk by 10 degrees, the cracking pressure would be that required to lift the weight of the disk a hair over 10 degrees.

I don't know what the weight of a swing check disc weighs, so let's assume it weighs twice that of a nickel, 0.176 oz or 0.011 lbs. The I.D. of a 1/2" copper pipe has an area of ~0.233 sq. in. The sin of 10 degrees is a bit under 0.174. So, with these assumptions the cracking pressure of a 1/2" swing check valve would be (0.011/0.233) x 0.174 = 0.0082 psi.

But some of my assumption may be off, so using a safety factor of 10, I would say the cracking pressure of a rudimentary 1/2" swing check valve would be something like 0.082 psi.

Makes sense... Love the detail! Good news is my return line appears to be slightly sloped downwards along the floor so I'm thinking this might give me some assist on cracking.... this is the valve I just picked up at the local big box store

OK, now can you kindly explain Twowaxhack's suggestion to remove the heat nipple trap? I'm not understanding how this would affect the circulation.... I'm hesitant to remove it without better explanation. I watched few YT videos and looks like this can be a PIA but maybe I'm missing something.

 

[Twowaxhack]

Heat traps are designed to keep hot water in the tank. You want it to circulate by thermosiphon

Do you watch college football ?

 

[DIYQuestionGuy]

Heat traps are designed to keep hot water in the tank. You want it to circulate by thermosiphon

Do you watch college football ?

Are you saying it won't circulate with heat traps? But yet, it allows supplies to receive hot water. That's the part I'm not understanding.

Yes sir, I do watch college football, and high school, and NFL.... I watch ALL the footballs!

 

[Twowaxhack]

Are you saying it won't circulate with heat traps? But yet, it allows supplies to receive hot water. That's the part I'm not understanding.

Yes sir, I do watch college football, and high school, and NFL.... I watch ALL the footballs!

That’s what I’m saying,yes. There are several types of heat traps. When you open a faucet it opens the heat trap and when you close the faucet the heat trap closes. You’re trying to get hot water to migrate out of the tank during no use and heat traps are manufactured to prevent exactly that. That’s the simple explanation.

I’m trying to figure out what to cook for the games this afternoon. Might do some tacos. I watch NFL and SEC. I have several customers in play in the NFL

 

[DIYQuestionGuy]

That’s what I’m saying,yes. There are several types of heat traps. When you open a faucet it opens the heat trap and when you close the faucet the heat trap closes. You’re trying to get hot water to migrate out of the tank during no use and heat traps are manufactured to prevent exactly that. That’s the simple explanation.

I’m trying to figure out what to cook for the games this afternoon. Might do some tacos. I watch NFL and SEC. I have several customers in play in the NFL

RE: Heat trap - thanks for explanation. I see what you're saying. The part I'm still questioning is - the loop is pressurized, right, even at rest. If water circulates through the return line wouldn't that allow water to flow through heat trap? I'm thinking, even if I crack my hot water tap just barely, water still flows... I'm just not quite understanding I guess. If I wanted to remove the heat nipple/trap, do I need to remove whole nipple or can I just disconnect the line and pull out rubber flapper or whatever with some needle nose?

Never can go wrong with some good grill items for game - brats? burgers? I'll even through some frozen pizzas on the Traeger and cook them sometimes for game snacks. Tacos good too. Where are you located? Guessing south if SEC??

 

[MicEd69]

If I wanted to remove the heat nipple/trap, do I need to remove whole nipple or can I just disconnect the line and pull out rubber flapper or whatever with some needle nose?

I've not messed with heat traps as I have a pump in my hot water circulation system. If you have the rubber flapper type, I expect you could remove the rubber flapper with some needle nose pliers and perhaps a razor knife. If it is a ball or disk type, that would be a tougher job, but I would say it would still be possible with something like a Rotozip or a drill with a serrated side cutting drill bit. Just be careful not to nick the plastic all the way through to the steel nipple. In either case, I would expect removing the guts of the heat trap would be easier than removing the nipple and re-piping the water heater.

 

[DIYQuestionGuy]

I've not messed with heat traps as I have a pump in my hot water circulation system. If you have the rubber flapper type, I expect you could remove the rubber flapper with some needle nose pliers and perhaps a razor knife. If it is a ball or disk type, that would be a tougher job, but I would say it would still be possible with something like a Rotozip or a drill with a serrated side cutting drill bit. Just be careful not to nick the plastic all the way through to the steel nipple. In either case, I would expect removing the guts of the heat trap would be easier than removing the nipple and re-piping the water heater.

Yeah, I'm pretty reluctant to mess with the heat traps unless it's truly needed. I'm assuming this would void warranty of water heater (still under warranty). No disrespect to Twowaxhack, I think he makes a good point, but I'm wondering if it's similar to the whole "cracking pressure" on the swing valve back and forth. Meaning how much pressure is required to open trap??

At this point, my plan is install swing valve on return, add a shut off valve (for future service) and see what happens. If this improves heat to my kitchen sink, great, I'm done. If not, I'll explore adding recirculating pump and sensor at kitchen sink.

 

[MicEd69]

I personally wouldn't worry about the warranty as I've never had a water heater failure covered under warranty. And if you are happy with a passive hot water loop, I would stay with it over a pumped system.

Another inexpensive thing that may help would be to insulate the hot water line from the outlet of the water heater for several feet. That may give you enough additional motive force to overcome the resistance of the heat trap.

 

[Twowaxhack]

RE: Heat trap - thanks for explanation. I see what you're saying. The part I'm still questioning is - the loop is pressurized, right, even at rest. If water circulates through the return line wouldn't that allow water to flow through heat trap? I'm thinking, even if I crack my hot water tap just barely, water still flows... I'm just not quite understanding I guess. If I wanted to remove the heat nipple/trap, do I need to remove whole nipple or can I just disconnect the line and pull out rubber flapper or whatever with some needle nose?

Never can go wrong with some good grill items for game - brats? burgers? I'll even through some frozen pizzas on the Traeger and cook them sometimes for game snacks. Tacos good too. Where are you located? Guessing south if SEC??

When you open a faucet you create a pressure differential and the heat trap opens. When there’s no flow the pressure will equalize and the heat trap closes. They don’t close 100% but it greatly reduces hot water rising out of the tank.

 

[wpns]

Sounds like the heat trap has a cracking pressure, which will (is designed to) prevent hot water from escaping, which is preventing your passive thermosiphon from working.

 

[Twowaxhack]

Heat traps don’t close 100% or it would create a closed system but they’re effective at reducing hot water migration out of the tank. With a thermosiphon you want water migrating at least out of the hot side, that’s how it works.

So the two are fighting each other.

 

[Mitchell-DIY-Guy]

I should also mention the possibility of trouble if using pipe insulation...I said possibility not certainty.

Remember the whole thermosiphon thing works based on the fact that hot water rises, and as it rises to the top and loops back over (cooling in the process) and down to the bottom of the tank, there is then what you may call a "hot side" and a "cool side". If there's little to no temperature differential--the water temperature in the return loop the same as the supply line, I could see how perhaps the system wouldn't work so well.

There have been reports of some thermosiphon systems that have their check valve "chattering" (in which case the small hole drilled into the flap has been suggested as a solution. There may be some talk of this in older threads...

 

[MicEd69]

I should also mention the possibility of trouble if using pipe insulation...I said possibility not certainty.

Mitchell, you are correct if you are talking about insulating the entire loop. You need to have a "flow" of hot water out of the water heater where it will be cooled in the piping sending it back to the water heater in the reduced sized return line. Insulating the hot water line coming out of the water heater for a length would not be a problem. But insulating the entire loop would drastically reduce the motive force of the thermosiphon.

 

[Mitchell-DIY-Guy]

Mitchell, you are correct if you are talking about insulating the entire loop. You need to have a "flow" of hot water out of the water heater where it will be cooled in the piping sending it back to the water heater in the reduced sized return line. Insulating the hot water line coming out of the water heater for a length would not be a problem. But insulating the entire loop would drastically reduce the motive force of the thermosiphon.

I pretty much thought so, but no empirical evidence to prove it.

When I was under contract to have a home built here, the plumbers had a hard time understanding what I wanted to do; I simply asked for a ½" return line from the furthest point on the second floor, However they gave me some absurd price (considering the cost of PEX) and said it's because the NC code required the entire return line to be insulated. I told them I didn't think it would work then. I ended up not building the home. We wait forever for hot water in the kitchen and upstairs; primary bath is behind the water heater in the garage and is quick. Just have to live with it.

The somewhat clueless builders here say it's about energy efficiency, but one of the "energy efficiency" items they are required to install is a fresh air vent system (WITHOUT an HRV). I had that without knowing about it, then one day, I noticed that warm moist air is being sent into my office registers, and I said WTF? So they think it's a smart idea to bring in unconditioned air (hot and humid in summer, cold and damp in winter) into my conditioned living space? They think that's somehow efficient? It's ungodly stupid if you don't use an ERV or HRV, certainly in this climate. I immediately disconnected and shut down that system. My house may be built tight but the doors open all the time so I don't have to worry about any fresh air. I just don't want unconditioned air coming in my space!