Controlling Hot Water Recirculation Pumps

Hello. I just bought a new home that has a recirculation pump located near the hot water heater. I am new to all this so I have some questions:

(a) I have looked online and see some of these pumps have timers attached so they operate only during expected usage times (not between midnight and 5am). Mine does not have one that I can see. Are these always attached directly to the pump body or can the timer be located elsewhere? If elsewhere, where might this be?

(b) I have read that some of these systems incorporate a temperature switch somewhere that shuts off the pump when a pre-set temp is reached at some point in the line. What are the signs that mine has such a switch?

(c) Even with a timer as in (a) above it seems potentially very wasteful and hard on the pump for it to run continuously as we are not big hot water users generally. So is there some simple way - ideally using X-10, Active Home, CMA-11 (I think that's it), and simple macros (no running computer needed) which I already use - to control this pump mechanism at a more granular level?



Reply to
David White
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I installed one of those Grudfos pumps here. The master bedroom and laundry are a long run from the hot water heater. In this desert climate, I hated to dump that much water down the drain waiting for the water to warm up. Our schedule is variable, so we may need hot water any time of the day.

I changed the runs to two complete loops which service opposite ends of the house, The Grudfos pumps both loops. A gate valve in the return balances both so they heat up at the same speed. The pump runs for 75 seconds every

15 minutes, just long enough for freshly heated water to purge the line. All piping is well-insulated so there is little decrease in temperature over that interval. I probably could stretch it out to 20 minutes or even a half hour by allowing more variation in temperature.

Rather than hearing that clack clack every 15 minutes, I run the Grudfos off an old BSR X10 lamp module. Obviously, it is only sent ON and OFF commands from the Ocelot. It has worked fine for almost 4 years now.

Regarding a timer or possible temperature sensor, check if there is any other wiring or a dial on the pump. If it just has a simple wire connection that connects to 120VAC, it probably runs 24/7


Reply to
Jeff Volp

Our Buderus boiler (which also makes hot water) does this automatically. The computer runs the pump for user controlled intervals at user defined intervals of our choosing. I believe it is set to run for 3 minutes every half hour from 6:30 am until 11 pm.

The pump is located behind the furnace on the wall with an auxilliary switch which allows the pump to be shut off permanently. I would expect the pump to be located somewhere near the water heater with the timer close by.

Reply to

Type the model # on your pump into google or go to the manufacturers web site and find the manual.


Reply to
Bob F

On many systems there is no timer. The loop runs continuously. You can get a timer added easily.

On my system I've added a timer and a pipe mounted thermostat. The timer turns the loop off at night. The pipe stat is clamped to the pipe where the hot loop returns to the hot water tank. It turns off the pump during the day once the hot water has gone around the loop an heated the return. Eventually the loop cools again and the pump restarts. The pipe stat is overkill really. A system is perfectly ok without.

These recirculating pumps are quite low power and are designed to run continuously. The power should be written on it somewhere. I guess you could use an appliance module to control it and switch it off at night. Definitly overkill though!

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