How does my combi boiler work?

[Larry the Dwarf]

No doubt everyone who reads this will think I'm incredibly thick but...

I have just moved into a flat with a combi boiler and have never used one before. We have a problem in that the hot water does not seem to last for more than a couple of minutes.

Should I only try to use the hot water when the central heating is off? If I should I have the CH on, what kind of temperature would be sensible in order to achieve enough hot water for two adults to shower etc in the morning.

Should the radiators get hot when running hot water with the CH turned off?

Can anyone help, or do you think there is a problem and I should get an expert to have a look at it?

Thanks,

Larry

[IAN CAPEL]

You will get a huge amount of help if you could tell us the make of the boiler

[Tony Bryer]

If it's a combi it will (should) switch to heating hot water when hot water is required whether or not the heating is on or not. Usually you have control knobs for heating and hot water temperature and/or one that sets off/DHW only/Heating + DHW

It might help if you can say what make and model it is.

[John Rumm]

When you say "last" do you mean that it works for a bit and then goes stone cold, or do you mean it just seems to cool off and not stay hot enough for a bath etc?

If the former, there is something wrong with the boiler.

If the latter this can be normal for a small combi when asked to deliver hot water faster than it can heat it properly. The solution here is to not turn the tap on as full, so that you get a slower flow of hot water rather than a torrent of tepid.

Should not make any difference, When you turn the tap on, the boiler will divert all its power to the water heating. If the CH was running it will stop heating that for the duration. If the CH was off then it will fire up and run until you turn the tap off.

no relevant - the two are independant.

No, if this is happening then that indicates that the diversion valve has probably failed. It is this that is supposed to direct the heating effort of the boiler either to the CH or the HW.

Probably the latter unless you are reasonably confident with plumbing. If you are ok with fiddling then chaning a diversion valve may not be that difficult depending on the make and model of the boiler.

[Mike Halmarack]

Hi Larry, I'm sure that with help from this newsgroup, you'll get the problem sorted out just fine. If you can't and your flatmate is also a dwarf, couldn't you take turns to sit on each other's shoulders at shower time, so as to make best use of the currently available hot water?