Recirculating Hot Water

[Anonymous]

I’m plumbing a new house and have full access to all the piping. I want to keep hot water at each tap. I was going to use a pump with timer or thermostat, but I saw a brief mention somewhere of a simple convection system. It involves only bringing the water from the farthest point back to the cold water inlet of the heater. Presumably, this will cause recirculation. Is that correct? Where should we tap the return onto?

[hjParticipant]

The convection circulating system only works if the hot water line has continual up pitch to the farthest fixture and the cold water has continual down pitch back to the water heater. The connection to the water heater can be made anywhere that is lower than the point where the cold water returns to the heater. At the heater there has to be a check valve installed in such a way that the flap is normally partially open but will still close when a backflow condition occurs.

[DONSPLACEParticipant]

Thank you for the reply. That’s a tricky bit of planning; There will be a couple of baths plus the kitchen, on one level, total some 120′; farthest distance from heater to last fixture (cold return) about 80′.
I heard of that check valve – I think it was called a ‘soft check valve’ – is that the correct item to call for?

[SylvanLMPParticipant]

Hey Don I would really reconsider the use of ANY TYPE of check valve on a hot water tank. As water is heated it expands and your only safety on this tank is the T&P valve and they are prone to failures depending on length of service and water conditions.

Personally I always look for non mechanical means to prevent the back flow of hot water into the cold by the use of a 27″ heat sink.

You should also forget the idea of putting the circulator on a timer.

Here is a web site article I wrote that may help you reconsider your options.

http://www.masterplumbers.com/plumbing/plumbviews/rec_pump.html

[DONSPLACEParticipant]

Hi Sylvan. Yeah, I’ve already read your article, and wrote to you about it yesterday. An excellent argument for recirculation.
Are you saying not to try for a passive system at all; to use a pump?
I have in mind a system that’s using no power.
I understand, I think, the problem with hard water deposits fouling a check valve, but won’t that also be a problem with a pump?
Maybe I don’t quite get the gist of what you’re saying.
Do you mind expounding a bit?
Don

[Author]

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