recirc pump, remote control

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Mitchell-DIY-Guy

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Depending on the rate of flow, some may be concerned with the so-called standby loss. In which case, insulation would be a big plus.
I think it's a great approach though.
Yes of course if you can insulate that return line, (and the hot water line) it makes a good thing better. I don't think my standby losses were appreciable however.
 

Mitchell-DIY-Guy

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Depending on the rate of flow, some may be concerned with the so-called standby loss. In which case, insulation would be a big plus.
I think it's a great approach though.
There's no free lunch. If you want hot water, you need to "waste" water by running it until it gets hot. If you want instant hot water, you have to have a point of use water heater, or a recirculation system. With the latter, you'll have costs and complexities if you have a pump. Even with a pumpless thermosiphon system (which not everyone seems to understand but trust me it works better than any pump system) you'll have standby losses. Even if your hot water lines are insulated as well as the return line, there STILL will be some kinds of standby losses. Every situation is different and you'd have to have a tremendous amount of accurate data (insulation R values, length of pipe runs, an almost impossible to measure flow rate, etc.) in which to create a framework in which to calculate what these losses will/would be, or how much electricity its going to cost to pump wasted water. It's a fools game and only one some OCD engineer would even try to attempt.

Bottom line is instant hot water is going to cost you something for the convenience. And we all pay for some level of convenience. "Accept it"; either the inconvenience or some trivial added cost for the convenience. Your choice.

And some of this stuff is a bit crazy; at my new home in the Carolinas, there's natural gas here. But, one of the builders in this subdivision is installing electric water heaters--that makes not a whit of sense. None. Here also, the Carolinians have not accepted gas clothes dryers even when gas is available; they'd rather heat the air with a 30A 220V electrical circuit. Also doesn't make a lick of sense. I had to install a gas line for the dryer in a new home in which there is gas here! There seems to be no shortage of the inexplicable; the things that make you shake your head.
 

joe99

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Well, I am doubting thermo-siphon will work in my case, given the layout. However, I am thinking and on demand Wireless pushbutton and relay, would be fine.

Right now I am considering eliminating my "cold sandwich" 5 gallon tank, strapon pipe aquastat (for return line temp sensing" and just going with a relay that will, upon trigger, stay "made" for a set time and turn off. The time to be determined by experimentation with the recirc pump run time and "hand on pipe" sensing. Pretty sure that will amount to a long enough time to clear the "cold slug" past the last tap and if not run it a bit longer.

Anyone know of such a relay, reliable, variable set and reasonable cost? I find them, but never used them, so no idea which are reliable in the real world. These do not have to be wireless as I would energize them via the wireless relay.
 

Mitchell-DIY-Guy

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@joe99 if you have the proper conditions--a "head" where the remote fixture and start of the return line is at least one level (a floor?) above the hot water source, AND you have the thermosiphon plumbed properly with a swing check valve, it's physics. It will work; there's no way it cannot work...

Many don't understand it, even a number of plumbers trying to "engineer" a complex system with pumps, etc. I laugh at this. I had circulating hot water for 27 years. No moving parts but the water. No maintenance. So simple it's hard to understand for those that don't get it.
 

joe99

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There's no free lunch. If you want hot water, you need to "waste" water by running it until it gets hot. If you want instant hot water, you have to have a point of use water heater, or a recirculation system. With the latter, you'll have costs and complexities if you have a pump. Even with a pumpless thermosiphon system (which not everyone seems to understand but trust me it works better than any pump system) you'll have standby losses. Even if your hot water lines are insulated as well as the return line, there STILL will be some kinds of standby losses. Every situation is different and you'd have to have a tremendous amount of accurate data (insulation R values, length of pipe runs, an almost impossible to measure flow rate, etc.) in which to create a framework in which to calculate what these losses will/would be, or how much electricity its going to cost to pump wasted water. It's a fools game and only one some OCD engineer would even try to attempt.

Bottom line is instant hot water is going to cost you something for the convenience. And we all pay for some level of convenience. "Accept it"; either the inconvenience or some trivial added cost for the convenience. Your choice.

And some of this stuff is a bit crazy; at my new home in the Carolinas, there's natural gas here. But, one of the builders in this subdivision is installing electric water heaters--that makes not a whit of sense. None. Here also, the Carolinians have not accepted gas clothes dryers even when gas is available; they'd rather heat the air with a 30A 220V electrical circuit. Also doesn't make a lick of sense. I had to install a gas line for the dryer in a new home in which there is gas here! There seems to be no shortage of the inexplicable; the things that make you shake your head.
Points taken. I see lots of stuff done around here because "we always do it that way", even when it makes no sense at all. Pervades all trades too.
@joe99 if you have the proper conditions--a "head" where the remote fixture and start of the return line is at least one level (a floor?) above the hot water source, AND you have the thermosiphon plumbed properly with a swing check valve, it's physics. It will work; there's no way it cannot work...

Many don't understand it, even a number of plumbers trying to "engineer" a complex system with pumps, etc. I laugh at this. I had circulating hot water for 27 years. No moving parts but the water. No maintenance. So simple it's hard to understand for those that don't get it.
Yeah, I get it. But, I have a tankless on demand heater. While there is a 5 gallon tank in the line, to temper the cold sandwich and the siphon might work well with a hot tank, once it cooled, I still need a pump to trigger the on demand and get the hot water into the tank.

In a system with a directly heated tank (or a super store with a zone off a boiler) and aquastat on the tank, the siphon, properly routed, would likely work quite well.
 

Mitchell-DIY-Guy

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Ditch the tankless for a conventional. The simplicity is elegance. Tankless rarely have a payback. Use a thermosiphon system. No moving parts; no complexities, just a simple system that would work well. No pumps, no timers, no aqua stats...and you can focus your energy on more useful problems!

psst. You’ll have instant hot water.
 
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