Shower pump turns off every 20 seconds or so

[mikeyking2]

I've just had some boiler work done yesterday where the mains water had to be switched off. The shower pump (Monsoon make) now only switches on for 20 seconds then powers off and back on again for 20 seconds when I try to turn the shower on.

It stays on longer if I put the mixer to hot water only... any ideas? Air lock? I've tried to turn off the pump and then turn on both the showers that it's connected to but, once the power is back on, I get the same issue.

I'm trying to get the boiler man back out but initially he's saying he knows nothing about shower pumps... Anything I can try in the interim?

TIA

 

[Ben-gee]

Assuming that all worked correctly up until now , it is almost certainly air - which needs to be cleared.
I think that monsoon pump has a float operated reed switch, these can stick.
With the shower running under gravity ( ie pump off) switch the pump on and then operate the reed switch externally using a magnet- this can keep it on long enough to clear the air.

 

[mikeyking2]

Thanks Ben - it was working in the morning as I took a shower but after the boiler engineer came it no longer works.

It's a Monsoon 46416 and I've just tried what you've suggested. It's got two reed switches (I'm assuming one for each shower as it's a 2 outlet model). So, I found the correct one, did as you said, but still it keeps cutting out.

Turn it all the way to hot water and the shower stays on (but not amazing pressure) but then move it to cold and it dribbles out and the pump keeps cutting out.

Any other ideas? I'm concerned he's going to come out and say "I didn't touch your pump"....

 

[Ben-gee]

In fairness he probably didn’t touch your pump - things go faulty for many reasons, and it could very well be a coincidence.

That is an excellent pump, how old is it?

You are wrong about the connections. One end is hot (in and out), the other end is cold (in and out) - I think the reed switches are on the outlets.

It sounds like you shouldn’t muck about with it to be honest - let your plumber take a look.

They are generally robust, I have some 20yr old ones in my customers.

The only thing I can point to as a possibility is that if the hot gets too hot it can cause the little cage, that the ball for the reed switch sits in, to distort which will give the behaviour you are experiencing. So maybe some adjustment to hot water temperature has occurred?

 

[mikeyking2]

Thanks Ben for your help so far - it's very Interesting! The pump is about 10 years old. So should I have used a magnet on both of the reed switches at the same time? I was just doing one at a time?

Nothing has changed for many years wrt to the pump. I've got an Immersun to divert any extra solar power to heat the tank so the hot water does get quite hot (65C+ or so I guess?)

I read in the manual that another way to potentially fix it is to run the hot water only through a switched off pump for a while and then turning the pump back on. So I did that - the hot water runs perfectly through with the hot water running through but as soon as you introduce the cold it stops. The more cold water you mix in the more frequent the pump powers off.

So, I'm kinda thinking that it wouldn't be extreme hot water that's caused it? Could there be an air block in the cold mains feed going into the pump or would that be cleared out with the reed switch that I've opened up?

 

[rpm]

Remove shower head from hose, hold end of hose as low as possible in the shower tray/ bath. Run shower until it is all good.

 

[mikeyking2]

Thanks Ben & RPM. The engineer came out today and it took him all of 30 seconds to fix! I turned the shower on whilst he isolated the cold water feed briefly and then re-introduced it. That resolved the air lock. Simples

Appreciate you taking time to respond though and hopefully this thread will help others with your answers.