Shower problem

[milly143]

Hi. We had a pump fitted to our shower this weekend as the pressure from it was useless before the pump was fitted. The pressure is now great however you can't stand in it long enough to appreciate it because the water goes cold after 1-2 minutes. It's not possible to actually have a shower in it. Could anyone suggest what the problem might be?

[The Builder]

I guess you have a gravity system Milly (roof tank and immersion cylinder)??

[milly143]

eeekk - I will try and answer as though I know what I'm on about - Not sure about the roof tank (there is one in the airing cupboard or is that the immersion cylinder? I'm sorry. I've always been dumb with these things.

[The Builder]

ok Milly ;o) ..................... big copper thing in the airing cupboard full of hot water?
(With a jacket around it)

[milly143]

Yep! That's the one!

[The Builder]

More Qs ..........
Is it a dual pump that deals with H and C separately, or is it a single type that mixes H&C together, then sends them to shower?

[craft1948]

Get a bigger hot water tank.....

[The Builder]

Also, assuming you have a shower valve with separate H&C ............. what happens when you crank the valve right over to H ?
Any idea if it's a thermostatic valve?

[milly143]

Oh no, that I really don't know. Really should have listened more when the plumber was talking. Perhaps if I tell you what happens it might give you a clue....
The pump has been fitted in the airing cupboard on the shelf above the cylinder and there are hot and cold pipes around it - I know that much as they were labelled.
When I turned the shower on it was quite cool so I turned it up a tad and it then went really hot, so turned it back down and it settled to a decent temp, then goes freezing cold after a minute or so. Sorry if that means absolutely nothing!

[The Builder]

Sorry I'm not being much help here Milly. The trouble is, there are so many variables ......... pipe size, gravity head, pump position etc etc ....... only the guy who fitted it would know.
The basic problem is that the valve is not getting enough volume of H compared to the amount of C ........... the Hot water supply simply cannot keep up..........
............. or ............. from what you say, you might not have a thermostatic valve, but a plain old manual one. If so, I think you need to discuss it with the plumber.
It's one of those where I really would have to stick my head in your A/C to see exactly what the layout is.
You're on the right lines having a pump fitted, but it sounds like the system needs a little further tweaking.
I'd love to hear back as to how you got on. :o)

[bednobs]

i wonder if the pump means you are using all your hot water really quickly. After you've had a shower, is there still hot water int he taps?

[bednobs]

actually, just ignore me

[milly143]

Thanks, it's ok. You can only help so much with limited information. I have got hold of the plumber and he's coming to take a look tonight so I will let you know what happens.

[AlBags]

Basically ... there are three types of controls ..
1. Thermostatic Mixers (One control with a temp blend control.. supposed to keep water temp constant, will shut off it get too hot) The cartridge in these can and do fail.
2. Non-Thermostatic Mixers (ditto) Just mix and rely on manual temp setting completely.
3. Separate Taps for hot and cold, either mounted on surface or inset.

[AlBags]

These power pumps are quite demanding on hot and cold supplies.
They usually need 'dedicated' 22mm copper feeds straight from the hot cylinder and cold tank .. otherwise the hot can cavitate (can't draw hot fast enough) and the water goes cold. My guess is the supplies need balancing up first and testing.

[milly143]

Well the plumber came round last night and part of the problem was that the thermostat in the tank was set really low (due a problem with heat/pressure before the pump was fitted). He turned it back up to 60 and was marginally better but still not great so he believes there is a load of calcium in the bottom of the tank. Apparantly the tank is ancient and is not insulated at all. He said it wasn't heating at the bottom of the tank, which you could tell when you felt it. The bottom was warmish whilst the top was too hot to touch. So in short he is coming to replace the boiler in a couple of weeks. I'm lucky that we have a very good landlord who is paying for all of this without the slightest moan.