Probably going to have to call a plumber out but,

Combi gas boiler. Radiators work (hotest they've been!) Cold water taps fine, no hot water! Not even a trickle! I assume a frozen pipe somewhere, but where?

Total ignorance but why do we still get cold water if a pipe was frozen won't that mean no water?

Will the boiler explode???

Matthew

If your boiler is anything like my oil fired combi, it has a hot water priority setup in that with the heating on there is a change over valve that stops heat being supplied to the rads and puts it to the hot water.

If you turn the heating off do you get domestic hot water flowing when you turn the hot tap on??

could be anyone of a number of things, welcome to combi's. Can't stand them myself. Usual problem is a stuck divertor valve. What make is it?

Paulsoxo will be along soon, he very good on appliances as he sees more of them than me, but drop me a line and I'll see if I can help

Check for un-insulated pipes in your loft if you have one.

sounds like a frozen cold feed pipe into the boiler – or someones inadvertently turned the isolation valve off

trace the cold main feed to the combi and if there is exposed pipework vulnerable to freezing try and thaw it out

gently – edit

vokera excell 80 sp. trying to follow pipes…..

We now have hot water, but not much or very hot. (it appears my wifes sister recommended turning the water inlet valve off…I don't know why!)

When the taps are turned on or the boiler fires to heat the radiators it is as noisy as hell. Loud rumble with a regular 'pulse'. I seem to think this happened a few years back and the plumber said the diaphram had perished and that they usually last a few years.

Does this ring any bells?

Yes

My Boiler uses a diaphram control on the diverter valve it appears to be a easy job to replace and it does not envolve touching the Gas so it could well be a DIY job, well it would be for me because I am a tight git ( just serviced my oil combi )

It could possibly be a number of things, but most likley as said the diaphram has puctured.

vokeras not good news – but prob fixable

id have to advise getting a gas safe registered installer to look at it

could be any number of faults in the water section of the boiler

but any work on a gas appliance comes under the regs

but any work on a gas appliance comes under the regs

even the controls system ??

Excuse my ignorance but I do not know, controls can also include the timer / sat etc even diverter valves

incorrect about ANY work, not that I would condone starting to work on an appliance wothout a fair bit of knowledge. The Gas Safety Installation and Use regulations cover just that, gas and safety, which generally means the gas supply, flues and ventillation.

Anyway back to the appliance, as it is noisy have you checked the pressure? But looking like the diaphragm.

I think a certain degree of common sense comes into it. If you Know it doesnt Affect the gas in anyway get stuck in, At your own risk of course

saladdodger

external controls – no

gas appliances – yes – if you have to take the boiler case off to get at it youre in 'competence' territory

Ok thanks for that

glad I own a oil burner but needless to say that comes under differant regulations 🙄

didnt mean to sound officious but thems the rules for gas

oil is a dark art to me anyway 🙂

No offence taken

I am a electrician and I too am trade protective

folk can smell gas, see water but electricity not nothing till it goes wrong

could also be the fan/fan impellor full of cack/fan venuri full of cack. Does sound like the domestic diaphragms not making though.

The ones on the excell tend to stretch rather than tear, so try running two taps full tilt for a few seconds to fire the boiler, then shut one off and then see if it heats, may get you some hot water until the gas man can get out

If you're going to call a plumber I'd suggest calling British Gas.

We had a problem two weeks ago with our heating. They came within an hour.

Got to go with the Diverter valve aroud £ 60 + for part
If you have the manual do it yourself other than that
get a plumber Wouldnt use British Gas unless you want to
pay double.

diaphragm way cheaper than £60.

Oil comes under different regs, but you MUST be OFTEC registered to work on an oil fired burner.

Grantaway

An excell doesn't have a diverter
you can get a full service kit for the diaphragm in the Water side, Pump Diaphragm, and bobbin in the flow manifold, which does the job of a diverter

BG charge a stabndard flat fee, which will be as cheap as, if not cheaper than some engineers and strictly speaking, you have to be registered to start sticking your hands inside any gas appliance, regardless of what you are doing. Hence why myself and bear aren't offering a step by step guide to change the diaphargm. even though it's a very simple job, which I can do easily in 10 minutes.