I have a Grundfoss 1.5 STC shower pump which has been working fine for the last couple of years. We have recently had some plumbing work done which required disconnection of the pump, and since then, after a couple of OK showers, it no longer works properly. The hot water feed seems to be the source of the trouble as it can slow down or stop altogether with the note of the pump changing to a rough uneven sound. With the pump switched off and only gravity feed driving the shower there is a sort of crackling noise on the hot water side which I took to be a sign of air in the system and the source of my problem. However, after extensive investigation I am now beginning to doubt this and wonder if the pump itself has developed a fault independent of the plumbing works mentioned. Does anyone know if this crackling sound is symptomatic of a pump problem and what it might be? The plumbing to the pump is by Surrey flange on the HW side and separate feed from the cold tank on the CW side. By the way, I'm trying to get the plumber back to advise me on this but he is proving elusive!
Shower pump not working properly
- Thread starter HLyne
- Start date
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That's what I thought initially, but I can let water run through it under gravity with the pump switched off for several minutes, but when I then switch the pump back on the problem recurs. I would have thought this would rule out any air being in it. If not, then how do I get rid of the air?
Crackling doesn't sound like it's an air issue, more like a motor issue.
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The trouble is I can hear the noise when the water is circulating under gravity with the pump switched off. Crackling may not be the best description. It is similar to the noise when water is heating up in a saucepan or kettle before it boils which is why I suspected air in the water for a long time. Would water at 55-60C make such a noise when flowing through pipes? If it isn't air I wonder if faulty reed switches vibrating in the flow or a damaged impeller spinning freely could just possibly cause such a noise. I could take the pump out and take it to pieces but I'd rather not if I can help it.
In case anyone is still monitoring this thread or, more likely, anyone is seeking a solution to a similar problem, I thought I'd add how this one was finally resolved.
I finally came to the conclusion that it just had to be air in the system and eventually discovered how to get rid of it successfully. The two key points seemed to be to (a) disconnect the hose to the shower head from the mixer, and (b) set the temperature control of the mixer to maximum by overriding the thermal safety stop. Then, when the water is allowed to flow through under gravity with the pump off, the hot water is unimpeded by either the shower head or the thermostatic control. This allows the air to be successfully expelled from the system after allowing it to flow for two or three minutes. Don't forget to reset the thermal safety stop afterwards.
Apologies to all those who thought this was obvious anyway, but as it eluded me I thought it might elude others too. I'm still not sure why the flow of hot water in pipes should produce the sound it does, but, for now, I'm just grateful for a fully functioning shower again
I finally came to the conclusion that it just had to be air in the system and eventually discovered how to get rid of it successfully. The two key points seemed to be to (a) disconnect the hose to the shower head from the mixer, and (b) set the temperature control of the mixer to maximum by overriding the thermal safety stop. Then, when the water is allowed to flow through under gravity with the pump off, the hot water is unimpeded by either the shower head or the thermostatic control. This allows the air to be successfully expelled from the system after allowing it to flow for two or three minutes. Don't forget to reset the thermal safety stop afterwards.
Apologies to all those who thought this was obvious anyway, but as it eluded me I thought it might elude others too. I'm still not sure why the flow of hot water in pipes should produce the sound it does, but, for now, I'm just grateful for a fully functioning shower again
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