DHW loop pump tip/warning

[Temp]

Woke up to no mains water today. Short while later noticed our DHW loop pump was making a lot of noise. Looks like flushing the loo caused water to drain back out of the DHW pipes causing the loop pump to run dry. 

 

Think I need to fit a one way valve or a pressure sensor to turn off the loop pump if there is no mains pressure.

 

Water co says no water for 10 hours 😞

[Jimmyjazz]

There should be a non return valve (check valve) on a secondary loop. Even if someone opens a hot tap during the period that the mains if off the secondary loop will drain of water and the pump will run dry. You could put a pressure sensor into the pipework like combi boilers have that would break the circuit if the pressure falls below 0.4 bar. Or alternatively if you know the water is going to be off, turn the power off to the secondary loop pump.

[Nickfromwales]

The non return on a HRC loop only prevents water trying to climb both legs of the pipe whenever the HRC pump is switched off. The loop would have syphoned out regardless tbh. Not a daily occurrence, so I'd just leave it well alone and wait for normal service to resume.