Ok, remove the shower head and use a wet vac on the end of the shower hose then turn on the hot and cold. This should start the pump, remove the wet vac. This will show that you need a negative head pump.
Andy
Andy
Pumped shower now won't supply hot under any circumstances
- Thread starter joefuller
- Start date
There is probably a sticky/faulty thermostatic shower valve as well, it should stop any cold water mixing with the hot on start up (except its set to cold), you might try isolating the cold water to the shower, put the shower control to its hottest, there should/might be enough flow then to start the pump, it will only keep running then though for a matter of seconds as the TMV will then shut off the hot, if you sort out (if faulty) the TMV then maybe install a PRV set to say 1.5bar in the cold supply to the shower.
@Johntheo5 the bath hot tap supplied by (horizontal...) gravity from the HW tank in the airing cupboard adjacent supplies 4 litre pm, calculated using a measuring jug and stopwatch.
OK, but its the (gravity) HW flow through the pump that starts it, remove the shower hose&head and see if it still starts, if it does just try it without the head only.
The HW tap has no restriction, the water just falls out the end.
The HW tap has no restriction, the water just falls out the end.
Just tried that John and removed the hose and handset, nothing happened. I tried with various settings of all the taps but the pump didn't kick in. For reference, these pics show our setup. The HW cylinder is in the airing cupboard with the louvred door, right next to the bathroom. The pump is under the bath.
Attachments
If this works and it stays running , that would usually prove a universal pump is needed.
If that shower has that rain shower head then they are designed for mains pressure water and need at least 1 bar to operate to any decent degree. Given that is near the ceiling and the CW cistern is just above then you'll be lucky to get any more than 0.1bar of HW at the shower head, at that rate it just isn't going to work properly, there just won't be enough flow to start a positive head pump.
Honestly, it's simply been a pi$$ poor design and I'm afraid the guy who installed it doesn't really know what he's doing. It is a relatively straight forward fix but it will probably need the pump changed (needs checked by removing the shower and running the HW from the supply pipe itself) but it shouldn't really need fixed, it could easily have been right from the start.
I hear you Madrab! I will try that test and report back.
We almost never used the rain head but what I don't get is that until recently, this set up did work (generally by turning on the shower full on in either rain or handset position then putting the thermostat handle to full cold then turning it to hot when the pump did kick in) and both the handset and rain head did supply good temperature HW at what was obviously pumped pressure. Not sure what's changed! Will check the fuse for the pump again though.
Thanks to all who have commented, at least I have some tests to try now.
We almost never used the rain head but what I don't get is that until recently, this set up did work (generally by turning on the shower full on in either rain or handset position then putting the thermostat handle to full cold then turning it to hot when the pump did kick in) and both the handset and rain head did supply good temperature HW at what was obviously pumped pressure. Not sure what's changed! Will check the fuse for the pump again though.
Thanks to all who have commented, at least I have some tests to try now.
Sorry - but I'm not talking about the fuse - I'm sure that fine.
By turning the pump off at it's power supply, running the shower with it on hot and then turning the power to the pump back on, the pump should spin up and that kick starts the pump as long as the hot outlet is open. All shower pumps used to be positive head pumps but when the water supply was in a negative head state the pumps had to be manually activated. This was done by a manual flow switch in the bathroom which basically bump started the pump and once running the flow switch is closed and it kept running until the shower was switched off. Doing that with the power switch should perform the same function.
Thanks Rob, I've tried your test a number of times this morning and no joy. No difference at all under any circumstances and the pump definitely does not kick in. To satisfy my curiosity, I did check the fuse and it is indeed fine. I note everyone's comments about a negative head pump being more likely to be what was needed but am now wondering if this pump has died. If not, why was it working until recently (admittedly with fiddling with all the taps) and now doesn't?
IMO, your best bet to rule a pump problem in/out is to install a T piece somewhere after the pump discharge with a valve on the end of the T, Put a bucket under this vale outlet, open this valve slowly until (if) the pump starts, then switch the pump off and measure this flowrate, should be 0.8 to 1.0LPM.
Quick update:
They came back last week with 2 men, removed the bath panel and tested the pump. Nothing wrong with it electrically. Then they reduced the CW flow going into the shower mixer. That allowed the pump to kick in if you briefly crack open the HW tap to the bath. That worked for 2 showers and now doesn't work again.
I don't get why these fixes work for a brief period and then don't work any more. Can anyone explain?
They're coming back tomorrow and have a different shower from another job which they're going to try which sadly doesn't have a rain shower outlet like this one does, just a handset. I'm tempted to give up on this and just have them install an electric.
They came back last week with 2 men, removed the bath panel and tested the pump. Nothing wrong with it electrically. Then they reduced the CW flow going into the shower mixer. That allowed the pump to kick in if you briefly crack open the HW tap to the bath. That worked for 2 showers and now doesn't work again.
I don't get why these fixes work for a brief period and then don't work any more. Can anyone explain?
They're coming back tomorrow and have a different shower from another job which they're going to try which sadly doesn't have a rain shower outlet like this one does, just a handset. I'm tempted to give up on this and just have them install an electric.
You need a Negative head pump.
Andy
Andy
DIYnot Local
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