Two pumps?

lbutton · 19 Oct 2005

Well, I'm stuck!
There are two pumps near my hot water tank on the same pipe source. The upstairs bathroom radiator gets warm when the HW is on and the CH is off (gravity valve?). Only the upstairs bathroom radiator gets warm when the CH is on and nothing else, not even the pipes warm up anywhere else.

Should also mention that one of the pumps is newly fitted and thermostatic valves have just been fitted to all radiators except the bathroom (where the hot water cylinder is).

Can anyone shed some light on this? I'm bothered by the two pumps mainly, seems badly done!

meldrew's_mate · 19 Oct 2005

Maybe it is badly done, what's the history -has it ever worked properly? Trace the outputs from the pumps and describe this accurately. Are the pumps attached to the same source (there's an arrow on the body to show pumping direction)?
Is it a std. copper hot water cylinder?
At this stage we don't know your level of expertese, so could it be a thermal store for example?

lbutton · 19 Oct 2005

Thanks for your interest.

It is a standard 'grade 3' copper cylinder.
There is a pipe into the top from the water supply.
A pipe from the middle(ish) comes out in a 'T', right to a Grundfos 15-50, left to water supply (water tanks are directly above cylinder.)
The pipe out of the pump drops straight down through the floorboards with a junction off to the second, new, pump - a Grundfos 15-50.
The output from here also drops beneath the floor.

I can't see any arrows indicating direction.

Is there anyway to put images into this forum? I could provide one if necessary of OK quality.

And, I am not very plumbing minded, I'm trying to gather as much info as possible so that I know what's happening when I call a professional.

Cheers

ChrisR · 20 Oct 2005

We're still in the dark about how it's supposedto work. Bathroom rad operation could be correct.
But when CH is on by itself, one of the pumps should be running - is that the case? If not sure, change speed on the pump and you will hear it stop/start. Or remove centre screw and insert screwdriver.

If neither running then check for Live on terminal under plastic cover. Mains test screwdriver will do.

If in doubt, don't go in there.

lbutton · 20 Oct 2005

On my timer near the boiler, downstairs, beneath the cylinder I can select for 'HW' or 'CH and HW'. I can't put the CH on without the HW.

The first pump, nearest the cylinder has 'Hot Water' written on it (only found when i cleaned the dust off!).

I'm trying to understand....

1) Why I have two pumps and are they necessary?
2) Why does my heating no longer work since having TRVs fitted even though the system has been drained and bled etc?
3) Why can't I have CH without HW?

The two pumps scenario was working until the TRVs although the bathroom radiator and first bedroom were always cooler.

ChrisR · 20 Oct 2005

I repeat, we don't know how it's supposed to work in your case, we can't see it. We don't generally waste time speculating.
Check for a CH pump as suggested please.

2 pumps can be OK, or wrong.

lbutton · 20 Oct 2005

Sorry, I think i misunderstand you. I definitely don't want to waste your time.

I can post a picture somewhere if you like?

What info do you need on how it is supposed to work?

The second pump is for the CH. Which is why I can't understand the first pump being connected to the same pipe even though it has HW written on it.

Thanks for your time.

lbutton · 20 Oct 2005

OK.

The system is a gravity fed system which explains in my set-up why I can't have heating without HW.

There is no cylinder thermostat, instead there is a water temp. control on the boiler. Don't know how good or accurate this is.

The first pump is on the HW circuit, the second (just replaced) is on the CH circuit. Although when you trace the piping they essentially come from the same source it is just trunked off separately.

From what other info I have gathered, and if anyone can qualify, the bathroom radiator (nearest cylinder) is getting hot when the HW is on because of a faulty check valve.

The new items are the TRVs on all remianing radiators, hence my problem is probably an air lock or blockage of some description.

Can anyone tell me if the above seems to be typical of a gravity fed system?

ChrisR · 20 Oct 2005

With 2 pumps it probably is NOT a "gravity " system.

Perhaps it was once, and the timer was never changed after perhaps a HW pump was added. The bathroom rad could perhaps be connected so it heats whenever the boiler is on. Both pumps would have to connect to the boiler in order to do anything, innit. So they would appear to be connected together wouldn't they.

Perhaps perhaps perhaps - there are more perhapses than you can imagine!

Your problem seems to be that you have no CH. Are you going to tell us whether the non HW pump runs OR NOT??? Take the central screw out and poke something in to feel for a spinning shaft. This will also bleed the pump.

We cannot make progress until you try it.

You will not solve it sitting at a keyboard, you need to do a couple of minutes "work"!

lbutton · 20 Oct 2005

both working fine. hence the new one fitted, because the old didn't!

Nige F · 20 Oct 2005

It`s a directive from 2 Jags...........all heating systems shall have 2 pumps

www. odpm.gov.org.uk.nfg.cu.2jags

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Two pumps?

Similar threads