Shower pump problem & CH & HW Probs

Hi All, have some problems with the plumbing in the house, before you ask I have read the FAQ's but can't fathom it out, anyone any ideas on these problems 1- Shower pump is not working properley, sometimes ok but more and more it looses a lot of pressure and the temperature is impossible to balance, either very hot or very cold, plumber who fitted it is a real ass, put pump in loft, am going to check today whether it has its own cold feed or is shared. Any clues anyone. Cant get plumber back as he's moved to where ever cowboy plumbers go, I'll name and shame him as Brian Harnett so beware.
2-CH works fine when HW is not on, when HW is on CH doesn't seem to function properley, when HW on rads upstairs seem fine but the odd ones downstairs barely get above cold, as soon as you turn HW off they heat up, I was thinking that they may be something wrong with CH pump, not strong enough maybe, am talking real guesses here, have very little experience with plumbing only with plumbers.
3- CW tank overflow pouring intermittently with water (this has only happedned recently, the other 2 have been going on for some time), sometimes a drip, sometimes flowing, haven't had chance to look at this yet but some feed back would be good. TIA Tel
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In an earlier contribution to this discussion,

Presumably the pump is supposed to pump both hot and cold water - so that they are mixed in the shower tap to provide the required temperature? The pump should *not* be in the attic - because the hot water then has to go all the way up and back down again. The pump is probably cavitating due to lack of head - because the level in the cold header tank is not much above the pump. It needs to be completely re-plumbed with: * the pump lower down (maybe under the bath?) * dedicated cold feed from the header to the pump (do *not* feed the pump with mains cold water!) * preferably a dedicated hot feed to the pump from a Surrey or Essex (No, I don't know why they have county names either!) flange on the hot cylinder - although, in practice, you can often get away with tee-ing off the bath's hot feed

Is it a fully pumped system with a mid-position 3-port valve to switch the primary flow to CH, HW or both? If so, is the CH ok once the HW is hot, and turns off on the cyl stat even though it's still selected at the programmer? If so, there's too much water going to the HW circuit and too little going to the CH when the 3-port valve is in the "both" position. The HW flow needs to be resticted a bit. Is there a gate valve in the pipework going to the indirect coil in the HW cylinder? If so, try partially closing it. If not, you need to have one fitted.

Are you talking about the large cold header tank for the domestic hot water system, or the smaller feed/expansion tank for the heating system. If the former, sounds like the ball valve isn't working properly, and needs to be cleaned out or have its washer or the whole thing replaced. If it's the small tank, this could also be the ball valve - but needs to have a few more things investigated at the same time.
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wrote:

Checked this out by turning pump off and running shower, hardly any flow so this could be correct, any chance of detailed explanation so I can do it myself, if I put pump under bath i prosume i'll have to run pipes from water tank under floor as rooting them up through loft would defy the object, is this correct. Mind you the ass hole who fit it has piping coming from loft down a wall next to pump,wall now tiled!! What can you do to a plumber if he's completely bodged a job up, he's an old guy so i can't rip his face off, but legally what can i do.

Don't know about a fully pumped system, conventional boiler, HW cylinder and tank in loft, system is about 20+ years old

Its the CH tank (small water tank above boiler), very hot water in it.
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In an earlier contribution to this discussion,

I think I would start by taking the hot feed from the bath supply - because that might work perfectly ok. You should already have a pipe (hopefully 22mm) running from the hot cylinder, under the floor and up to the hot bath tap. Put a Tee-piece in this under the bath, and take the branch to the hot inlet on the pump. If there is already a dedicated cold feed coming out of the bottom of the cold header tank, divert this down to the pump. You will have to work out the best route. I managed to route mine down inside a stud wall which joins the bathroom to a walk-in wardrobe in a bedroom. I used flexible plastic pipe and made a removeable panel inside the wardrobe to get at the pipes and at the connections at the back of the shower mixer valve. If there *isn't* a dedicated cold feed, you will have to install one - which will involve draining the cold tank in order to fit an additional tank connector in the bottom. [You'll get a bit wet if you don't drain it!]. You'll also have to find the best route for the hot and cold pipes from the pump up to the shower mixer valve.

Are there any motorised valves? Is there a thermostat strapped round the hot cylinder (not the one inside the immersion heater)?

It should *not* have hot water in it! When the system is cold, it should only have a small amount of water in it - enough to cover the outlet in the bottom by a couple of inches. When the system is hot, the level should rise a little but not much. The vent pipe - which goes up and over, and points down into the tank - *must not* dip into the water. When the pump is running, there *must not* be a constant stream of hot water coming out of the vent pipe into the tank. This is called "pumping over" and is bad.
Let the system cool down, and remove some water from this tank to get the correct level. Make sure that the ball valve cuts off properly and that it doesn't immediately try to restore the higher level. [You may need to bend the float arm so that it cuts off at the proper level].
When you have got the level right, closely watch this tank while the boiler and pump are running to make sure that it isn't pumping over. If it *is* turn the pump down to a lower speed setting. If that doesn't cure it, report back here - because you will probably have to re-jig some of the pipework.
[My best guess is that the problem is simply just due to the level being too high - probably coupled with a dodgy ball valve - causing the vent pipe to dip into the water, and causing syphoning to occur. Sort out the level and the ball valve and you'll probably be ok].
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It could be that it is installed in the loft. Pumps prefer to push rather than pull. Also, this could be related to (3) if the ball valve is sticking. The tank may just run out of water.

A really likely candidate is the balancing of the system. Each radiator and the cylinder coil should have a balancing valve to prevent one device taking all the water. The whole system should be carefully balanced using these valves, which is an involved process described well in the FAQ. One thing to note is that some systems (mine included) will intentionally have no valve for the cylinder coil (or have it fully open) in a simple method of providing hot water priority. This is happening in your case.
A system like this will only be a good idea if your coil has rapid recovery and is properly controlled by thermostat. Otherwise, the circuit will remain open for long periods (or continuously) and starve the radiators, meaning that you should balance the cylinder down.

This could be two reasons.
1 - Dodgy fill valve doesn't shut off properly 2 - Hot water expansion causes hot water to come out of the vent or back up the feed because the cold water level is too high to allow for expansion.
In either case, you need to fix the valve to shut off at a reasonable level in the cold water tank.
Christian.
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Since starting to tinker with my plumbing have noticed that the HW and CH each have a motorised valve, if you turn HW on valve turns, and if you turn CH on its valve turns, does this make a difference, the CH tank water is very hot, looking at the marks on the tank it has been very near the top (obviously when overflow was flowing a lot of water, i have turned pump down on boiler and it does seem to have stopped at present, will this surfice or will i have to do more, shower is a nightmare, shower wall is tiled and I can't get to the mixer unless I remove tiles, am I right in thinking i can T off both Hot and cold supply to bath for shower, if I can they maybe hope of being able to reach mixer somehow, cheers Tel
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