Thread: Water Circulation Pump

I saw this connection between 2 water heaters and was wondering what it is and what it does. Anyone know? I think its called a water circiulation pump as that was written on the wall next to it.

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How were the top pipes connected?

This is a diagram of a hot water circulation system.

Originally Posted by Stephen G Sheldon

I saw this connection between 2 water heaters and was wondering what it is and what it does. Anyone know? I think its called a water circiulation pump as that was written on the wall next to it.

It circulates water

I'm not sure how the top pipes were connected. What is the purpose of this? Why do you not see it more often?

Instant hot water, no waiting for water to come from the storage tanks. It keeps water circulating in the system so when you turn on the tap you wait seconds rather than minutes for hot water to arrive.
You don't see more of them because they cost money to install and operate! Pretty much standard in upper end houses. Almost all multifamily with central plants have a form of this system. Can you imagine having to be the first one to turn on the hot water if the plant was 300-400 feet away and the pipe was large enough to serve 5-10 units? You could wait all day, but keep water circulating and you get hot water when you want it.

Originally Posted by Stephen G Sheldon

What is the purpose of this? Why do you not see it more often?

Originally Posted by Jim Luttrall

Instant hot water, no waiting for water to come from the storage tanks. It keeps water circulating in the system so when you turn on the tap you wait seconds rather than minutes for hot water to arrive.

Jim is correct.

You don't see more of them because they cost money to install and operate!

You don't? You should. I am surprised as, while it does cost more to install and cost a little (not much) to operate, the water savings in gallons of wasted water used not only offsets that cost but, in the areas with droughts, is wasting A LOT of precious water, leaving the running the water just to get hot water.

Forget about those 1.6 gpf double-flusher and think of all the water wasted down the drain just waiting for hot water to arrive.

I appreciate your explanation. Thanks.

Also note that some of those circulation pumps, not sure about that particular one, MUST have the shaft for the pump motor oriented horizontally.

Looks like this one: http://www.taco-hvac.com/uploads/Fil...ry/102-135.pdf

Under Installation (bold underlining is mine): "2. Mounting position – Circulator must be mounted with the motor in a horizontal position. It may be mounted vertically with the motor up, provided that the system cold fill pressure is at least 20 psi (138 kPa)."

You should also make sure the pump is meant for potable water & not a recirculating pump meant for hydronic systems, the pumps used on the hydronic systems look the same & are cheaper, but they do not have the stainless steel recirculating blades & will leave a rusty residue in the water.

It helps keep well to do people from having to wait for their hot water. The extra costs come in on water heater fuel consumption. Because of the circulation of hot water through the pipes, heat is lost. Gas water heater burners come on alot more often. The result is an increased fuel bill.

Originally Posted by Rob Turner

It helps keep well to do people from having to wait for their hot water. The extra costs come in on water heater fuel consumption. Because of the circulation of hot water through the pipes, heat is lost. Gas water heater burners come on alot more often. The result is an increased fuel bill.

With the hot water pipes being insulated as required, there is not that great of a waste of energy, but, yes, it does cost more, however, I keep going back to ... it sure beats wasting all that water ... which is in short supply in many areas all over the country.

Does anyone have a good way to test if the pump is working? Many times I find the pump after I have tested all of the fixtures in the house and I have no idea when the hot water was used last.

Come back the next day, or change your routine so you inspect the water heater earlier during the inspection. I don't know if there is an easy way once you've been in the bathrooms already.

Originally Posted by Jim Robinson

Come back the next day, or change your routine so you inspect the water heater earlier during the inspection. I don't know if there is an easy way once you've been in the bathrooms already.

Maybe I need to add " Seller and sellers family MUST NOT BATHE OR USE HOT WATER PRIOR TO INSPECTION!"?

Originally Posted by Vern Heiler

Does anyone have a good way to test if the pump is working?

You mean if it runs, or if it actually does what it is intended to do?

To see if it runs:
- First make sure it is plugged in ( I know, but you have no idea how many I have found NOT plugged in and the seller did not know it).
- Then unplug it and test the receptacle to make sure there is power, plugging it back in afterward.
- Then, if there is no timer on it (some have built-in timers on them and others do not) if it is plugged in it should be running. You will feel the slight vibration from the motor running as different than when it was unplugged and not running.
- If there is a timer, you will need to deal with the timer, or just report as being their, with a timer, not checked for operation.
- Sometimes there will be service valves which allow the pump to be taken out of service and replaced without shutting the water to the water heater off - make sure they are open (like the un-plugged ones, I have found some left with the valves closed and the seller did not know it).

Originally Posted by Jerry Peck

You mean if it runs, or if it actually does what it is intended to do?

To see if it runs:
- First make sure it is plugged in ( I know, but you have no idea how many I have found NOT plugged in and the seller did not know it).
- Then unplug it and test the receptacle to make sure there is power, plugging it back in afterward.
- Then, if there is no timer on it (some have built-in timers on them and others do not) if it is plugged in it should be running. You will feel the slight vibration from the motor running as different than when it was unplugged and not running.
- If there is a timer, you will need to deal with the timer, or just report as being their, with a timer, not checked for operation.
- Sometimes there will be service valves which allow the pump to be taken out of service and replaced without shutting the water to the water heater off - make sure they are open (like the un-plugged ones, I have found some left with the valves closed and the seller did not know it).

Thanks Jerry. I too have found them unplugged, and was pretty confident it was not working. You must have the touch of a safe cracker to feel that little motor inside that large casting. I have never felt a thing! Maybe they were all dead?

Originally Posted by Vern Heiler

You must have the touch of a safe cracker to feel that little motor inside that large casting. I have never felt a thing! Maybe they were all dead?

Shoot, most of them I could even hear running.

If you cannot feel it, set a cup of water on it, the vibration will show in the surface of the water in the cup. If the surface is still, it is most likely not running. Note that I have never tried this test for those pumps, but it works for everything else, so it should work for them too. Does not take much vibration at all to resonate in the water and show in the surface of the water. I'd try a Styrofoam cup first as the vibration against the bottom should make the bottom act like a drum beating back and forth and really get the water moving, however, if it has the opposite effect and dampens the vibration in the foam sides, then try a rigid plastic or metal cup.

I'll try that and let you know.

Originally Posted by Stephen G Sheldon

I saw this connection between 2 water heaters and was wondering what it is and what it does. Anyone know? I think its called a water circiulation pump as that was written on the wall next to it.

There is one problem with the installation of that recirculation system. It is returning the water to both tanks in a parallel connection. The problem is the piping after the tee, it should be an equal distance with equal fittings between each water heater. The corrugated copper quick connect line adds lots of flow resistance which also contributes to the system to be out of balance. They way its plumbed in now the one water heater is doing all the work which will shorten that tanks life.

My preferred way of installing two heaters in parallel is the first in last out method. Here is a PDF of what it would look like. http://www.bradfordwhite.com/images/...ng/2H_TCRC.pdf Nice thing about this set up is you can isolate and shut down a heater if one does start to leak. The recirculation line returns back to the cold of both heaters with out modifying the drain valves

One more note. check with the local codes on the gas piping. In Illinois the gas piping must be hard piped to the heater. Also I noticed the heater on the right is newer. I would really like to see a picture of how it is plumbed in on the top. If they attempted to plumb it in parallel, the home owner will have one of the two heaters fail prematurely.