Hot water issue

TonySpoons

I have a combi boiler (unknown model, I'm at work but can update later if it's relevant, but I'm not sure it is) - our shower isn't firing up the boiler when it is turned on. It was working ok but has recently stopped. We can get hot water to come out of it if the heating is fired up at the same time, I don't think it's the shower control as we can vary the temperature when the heating is on. Other taps in the house work all the time (although some of them need to be turned all the way to hot to provoke the boiler). Our water pressure has never been amazing and I wonder if it has now dipped below that suitable for the boiler; we had a plumber round who stated that the pressure next door was better than ours and that he thought it was a mains pressure issue.

Does anyone have any ideas? I've requested the water supplier to come and check the pressure but I suspect it will be an issue between the main and the boiler.

Anyone have any other ideas?

Carrot007

Do you have an old lead pipe supplying the house.

My previous property did and pressure was terrible untill i got it replaced.

Quite a simple job and cheap too if you are willing to dig your own trench!

bertiewhite

It's not the diverter valve, is it?

TonySpoons

Is the diverter valve in the boiler? I wouldn't think it was it as other hot taps in the house can get the boiler to turn on.

Alex1983

You need to tell us the boiler model.
The boiler will have a minimum flow rate required to make it work for hot water, the shower is either not pulling enough water to operate the boiler or the boiler has a faulty/worn hot water flow switch.

bertiewhite

TonySpoons wrote: »

Is the diverter valve in the boiler? I wouldn't think it was it as other hot taps in the house can get the boiler to turn on.

It was just the comment about getting hot water when the heating is on. I used to have a baxi combi boiler which would work fine with the taps but intermittently with the shower and then when I did get hot water from the shower it would often go hot/cold.

TonySpoons

It's a 'Main Combi 30HE'

The other taps can get the boiler to turn on just fine, but not the shower. Although the shower is happy to provide hot (even scalding) water if the heating is on, which suggests it's not the temperature control in the shower restricting the temperature or something.

Alex1983

That boiler needs a minimum flow of 2.5litres per minute to work.

Run a hot tap at around that flow and see if the boiler still works then you issue is the shower. If the boiler cuts out (hw led goes out) then you have a worn hot water diaphragm.

TonySpoons

My bathroom sink tap just filled 5 x 500ml jugs in 43 seconds without provoking the boiler into action and the bath tap managed under 30s...so it's the boiler then? Difficult/easy/costly to get repaired?

Alex1983

Easy job to repair. Diaphragm will be around 10 quid. Water off. Undo about 8 screws and swap the diaphragm. It's located right at the front, should take no more then a hour with the relevant safety checks to be carried out as well. Make sure they only do the diaphragm and not the complete vavle as that will be closer to £100. Don't know what a local gas safe guy will charge.

southcoastrgi

TBH if you are confident you could do it yourself