Timer connected to water heater?

[David Nasser]

Anybody know what type of set up this is?

[Brian E. Kelly]

Circulating pump.

[David P. Valley]

W/H supply piping will be at the top of the tank.

This appears to be a supply to something behind the wall. Where does this supply piping go?

[Michael R. Boyett]

I agree with Brian...it's likely a whole house hot water recirculating pump but I don't know why there are two timer mechanisms...one feeding the other. Perhaps the one on the pump itself is defective and the homeowner simply 'replaced' it with the outlet mounted appliance timer. Usually no need to circulate hot water to the fixtures at 3:00 am you know.

[Michael Larson]

Originally Posted by mboyett

I agree with Brian...it's likely a whole house hot water recirculating pump but I don't know why there are two timer mechanisms...one feeding the other. Perhaps the one on the pump itself is defective and the homeowner simply 'replaced' it with the outlet mounted appliance timer.

One thing is certain.
If the original timer is still functioning it cannot be at the right time very often.

[Bob Elliott]

Originally Posted by mlarson

One thing is certain.
If the original timer is still functioning it cannot be at the right time very often.

Probably stuck on as there are no pins.

[David Nasser]

Is this a system for instant hot water ?

[Bob Elliott]

The pump keeps the hot water moving through the system so you do not have to wait for it to travel from the Hot Water Tank.
So Yes.

Hmmm
No drip leg visible

[Michael Larson]

For those of you who have not seen a passive re-circulator, here is one from yesterday.

[Michael R. Boyett]

David...here's a diagram of a simple system. Google "hot water recirculation system" and you will get plenty of information.

[Bob Elliott]

The thing I have always had a hard time with is..
Why does the recirculation pump not push hot water back into the cold supply and only push it around the hot water supply pipes if there is no check valve on the cold water side.?

.

[Michael Larson]

Bob the loop is formed from the hot side of the far fixture back to the cold inlet of the water heater.

[Bob Elliott]

Ok
But since it adds ore pressure to the tank you would think that it would add that pressure equally to the cold water inlet and the hot water outlet .

That is the concept that I have a hard time grasping.
If the cold water side had a check valve I could see the pump circulating the hot water supply only. (But it has 2 paths it could potentially follow as the tank has 2 openings). (Ok 3 counting the pump at the bottom drain).

[Michael Larson]

Originally Posted by relliott

The thing I have always had a hard time with is..
Why does the recirculation pump not push hot water back into the cold supply and only push it around the hot water supply pipes if there is no check valve on the cold water side.?

.

Follow the yellow line. There is no open loop on the cold side.

[tdietrich1]

Originally Posted by mlarson

For those of you who have not seen a passive re-circulator, here is one from yesterday.

How does a 'passive' one work?

tom