Low water pressure from hot tap

CountingClocks

Hi folks,

Maybe someone can offer advise here

I have a Baxi 35/80 boiler, all working fine with hot water and rads but the water pressure to the hot tap has dropped to a trickle last week or so.

It was intermittent, now it's a trickle all the time. Cold water tap still has good pressure.

Pressure is between 1.5 and 2. No flashing lights, all temp symbols are red.

The power, radiator and flame lights are on. The tap symbol is not.

Any ideas?

RJF

Is the water in your copper cylinder hot - presuming this is not a combi boiler. Sounds like you have an airlock somewhere. Do you have poor or no flow at all taps or just the bathroom?

Sleeper12

is it all hot taps in the house or just one?

CountingClocks

Thanks for your reply.

The cylinder is hot and the water from the tap is piping hot, it's just that the pressure is really low. It's the same in all rooms, kitchen + two bathrooms.

This problem may have coincided with bleeding the radiators a few weeks back. If there is an airlock, how would I best resolve that?

Calahonda52

Check that the valve on the cold water feed from header tank in attic to bottom of hot water cylinder is fully open.

RJF

It has nothing to do with bleeding the radiators-this is a separate system. The water in the boiler, rads, heating pipework and cylinder coil does not come out the taps. The hot water flows out the pipe on top of the cylinder and goes to the taps. I presume your supply tank in the attic is full and the ballcock is not stuck since you have cold water supply but check it to be sure. The next thing to check is the supply pipe from the attic tank to the bottom of the cylinder. There might be a lever valve on it that got accidentally closed-long shot but check. Next do you have access to a wet vac? Let me know and we can go further.

CountingClocks

Thanks again, it's an apartment so there is no attic, the cylinder is in a cupboard inside the apartment.

I think I need to get someone in since I recently moved in here and I'm not familiar with how the system (or in fact any heating system) works, I definitely haven't touched or changed anything so looks like maybe a fault has developed somewhere.

Do I need a gas engineer or a plumber??

RJF

It has nothing to do with the gas or the heating system- it has to do with the pipework from the copper cylinder. Is the cylinder a tall one about six or seven feet and is there a pump in the cupboard.

CountingClocks

RJF wrote: »

It has nothing to do with the gas or the heating system- it has to do with the pipework from the copper cylinder. Is the cylinder a tall one about six or seven feet and is there a pump in the cupboard.

Yes it's a tall cylinder, a a Lycris-Byrne described as a Customised Pre-Plumbed Indirect Combination Unit with a cold tank, hot tank and pump.

RJF

Ok, can you have a look at the pump and tell me what make and model it is and how many pipes going in and out of it. If you could post some pictures it would be a big help.

CountingClocks

RJF wrote: »

Ok, can you have a look at the pump and tell me what make and model it is and how many pipes going in and out of it. If you could post some pictures it would be a big help.

Sure, I just took some pics so I'll stick them up.

CountingClocks

RJF

Sorry CC need to see the pipework at the bottom left of the cylinder and also going to the pump and the pump itself (water pump not circulating pump). Should have four flexi pipes with shut offs going to it. Can you do a few more pics and give me make and model of pump. Suspect a pump problem but need info to ask you right questions and give solution. Also can you confirm that the pump is wired to an isolation switch (electrical).

RJF

Check that that red gate valve on top of lower cylinder (bottom valve in pic) is open fully (anti clockwise).

CountingClocks

A few more pics, the red valve wasn't fully open so I've done that now.

nmacc

Oh dear, oh dear.

Pump is on its side with no shut-off valves.

Normally when the hot tap is opened the pump will start and you will definitely hear it. I presume that it no longer starts up when the hot tap is opened?
Does it start when the cold tap is opened?

Follow the black cable from the pump to the electrical outlet on the wall and check that it's switched on. Also check the fuse board for a tripped circuit breaker.

CountingClocks

Hi there,

When I turn on any tap now the pump doesn't start, it just emits a low buzzing sound but doesn't actually start up. It's plugged in and I've checked the fuse board as well.

New pump needed?

nmacc

Not necessarily a new pump.

If it's buzzing that means the motor is getting power, but failing to turn. Switch it off at the outlet; this won't reduce the flow any further.

There are several possible causes, but the most likely is a failed motor capacitor and following closely behind, a faulty circuit board.

You need a pump repair company, so call Modern Plant on 01 - 459 1344 and ask them to recommend someone. Give them the model number.

It's not a top-of-the-range pump and the repair company may advise replacing it rather than repairing.

anthonyos

You need a new capacitor fitted in the pump not a new pump.do you live in an apartment

CountingClocks

Thanks for the advice and contact details, yes I do live in a rented apartment.

RJF

Hi Nmacc, I don't think the pump is on its side this is just the orientation of the picture. Good advice to switch it off. Won't affect flow. Are modern plant still doing Stuart Turner or still in business? Since this problem started with gradual loss of hot water only and the cold still had good pressure I think this might be some sort of blockage on the hot side of the pump. Maybe a non return valve has broken apart and a spring or ball/cap has got caught in the impeller. Also possible some debris made it past the filter. Anyway its definitely the pump. You will need to find someone to repair and service it. If you can't find someone try back here for further advice.

RJF

The shut off valves for the draw side of the pump are the two red gate valves close to the cylinder. Doesn't look like any on the flow side. There should be.

CountingClocks

I plugged the pump back in this morning and when I turned on a tap there was a full water flow, I'm guessing since the problem has been intermittent this might be a temporary reprieve and I'll be back to a trickle again soon.

RJF

Do you have full flow on both the hot and cold?

CountingClocks

RJF wrote: »

Do you have full flow on both the hot and cold?

Yes full flow is back on both. I will try again after work.

CountingClocks

Flow was fine all yesterday evening then last thing it was back to a low flow in both taps. I'll give Modern Plant a call.

RJF

Turn off the power for the pump wait a couple of minutes then turn back on again. This should reset the pcb. The pcb probably needs to be replaced. Modern plant no longer doing ST spares contact shower doctor instead, but they won't have parts until next week.

CountingClocks

Thanks for all the feedback and advise. Update is that the landlady sent a plumber around and he replaced the capacitor, it's working fine now and I'm to give him a call if there are any further issues or the pressure drops again.

RJF

Glad to hear you got it sorted.