no hot water from combi system

[Mickmickmick]

no hot water from combi system.

central heating is ok.

mostly no hot water

hot water very hot when it works.

[k8tkoo]

Have you checked the pressure gauge on the boiler? Had the same problem with mine and the reason was it kept losing pressure, eventually so much so that it had less than 0.5 bars and wouldn't work at all.

[Galena1]

The system pressure is probably ok otherwise the heating would not work.  Presumably water is flowing from the hot tap but it is cold? If so there are several reasons but none that you are likely to be able to rectify yourself. Sorry.

[david7]

sounds like your water diverter valve can be expensive depending on type of boiler

[flaming]

Same for me with the Combi boiler I inherited with this flat, about 6 years old in 2003 when I had the trouble.  I had very little hot water in the bath (third floor) unless the bath tap was turned down to a slow flow.  The kitchen tap  (second floor) wasn't so bad. The rads. were warm but the boiler kept losing pressure (the gauge/dial  at the bottom of the boiler casing).  I tried topping it up like one plumber showed me.  Soon after, an horrendous noise came from the boiler. The next plumbers replaced this and that until the expense was not far short of a new boiler.   I did need those things because the model was an old type with the mechanical board and the wire things were about to catch light!  I got a new diverter valve and a new digital(?) circuit board new boiler almost, old casing.

But, pressure still was being lost.  By that time I had got insured with a Heatguard plan, and it was found that I had surreptitious leaks from two rads.  One rad. pipe was eaten by rust and I got a new rad. under the plan.   leaks jhad been just enough to send down the pressure more gradually but not enough (the heating pipes dried the leaks almost as soon as they occurred) to give me a clue about the leaks.  I am not saying I didn't need the other things, I could see I did, but the rad.leaks are worth looking for first.  Usually there's a water run-down feelable when the rad. pipes are COLD and have contracted enough to let water.

There is a qualifying period for the Heatguard Plan.  I have nice hot water now, but it does take a while to come through when the heating is off.  Only mains water is used.  If you have to have a new Combi, the condenser boilers are now mandatory;  as well as being environmentally superior, they are more economical to run.  Potterton have been taken over by Baxi.

[flaming]

I forgot - the noise before I had the new board (controlling the innards of the boiler) was very marked.  It was much smoother after. People will be very anxious to sell you a new boiler as they want the profit and the work of putting it in.  Maybe where you live plumbing/heating engineers are't scarce, but they are here, and I reckon I could have easily doubled the costof a new boiler with the fitting of it.  I was saved the awful business of changing boilers - and it was very cold when I first had trouble so I wanted immediate solutions.  You have to decide though whether you want to persevere with the old one or fork out for a new one. You could try the simple things first, but if it is not just the leaks around the system you have to decide about the next stage. Once you have started spending you get in deep and then have to go on.  If you have the boiler serviced, that might suffice for instance.  I think the people in the flat before me hadn't bothered, so the whole thing was made worse.  If there's not enough pressure over a long period it the boiler is 'starved' and becomes damaged.  I learnt all this the hard way!  Under my Heatguard plan I get an annual check, which I must get on with requesting before the winter.

[secretspirit]

This happens to me once a year and it's always because the water softener that's attached to the pipe going into the boiler is not working. Therefore the heat exchanger that heats the water scales up completely and won't heat the water although the heating runs as good as normal. Early symptoms usually include the boiler re-lighting a few times when the hot water taps are run or the water pressure getting lower. Unfortunately I can't find a plumber who will replace the water softener and it's not covered by the British Gas 3* service so I'm resigned to getting no hot water once a year (invariably at Christmas) and having to have the heat exchanger replaced.

[bjshipway]

secretspirit, you're problem sounds exactly like an issue i'm having with my Ferroli boiler.

 

i live in a very hard water area (I recently bought a new kettle and its already got limescale in it after a week!). When running the hot water the boiler 'sometimes' runs hot continuously and sometimes runs hot and cold turning itself on and off.

 

a lot of places seem to give the idea that its the heat exchanger thats been clogged up but you refer to a water softener. is that common to most boilers as I don't think mine has one.