Boiler Issue - How to explain to engineer...

pinkteapot

We're having our boiler and gas fire serviced next week. I have one issue with the boiler, and I don't quite know how to explain it to the engineer.

It's a standard boiler (not a combi). There's a dial on the front to the set the water temperature, which goes from 1-5 (nothing to do with the central heating thermostat).

We used to leave it on 4 which seemed to give us good hot water tap temperature in winter and decent heating.

A year or so ago, I noticed that when the boiler was running, it would regularly make a noise like a kettle boiling, then turn off. Then turn itself back on, make the same noise after a while, and cut out again.

I stopped this happening by turning the water temperature dial down to 3. That was fine over the summer, but now that the weather's getting colder, (a) the hot water from the hot taps isn't as hot as we'd like and (b) the heating is on but the radiators aren't getting quite as hot as previously.

Boiler hasn't been serviced since the boiling/cutting out thing. If I explain it as above, will that make sense to the guy?

ilikewatch

[STRIKE]If it's not a combi boiler does it heat the hot water or central heating? - your post makes it sound like it heats both (i.e. it is a combi!).

Explain it to the engineer just as you have above - he will tell you that the heat exchanger is scaled up, making the boiler kettle and that it needs to be cleaned or replaced.[/STRIKE]

alanobrien

Yes. tell him the boiler is kettling he will probably add some "silencer" to the system (descaler). If that doesnt work then a new heat exchanger is your best bet. Some may suggest a powerflush but that can cost more than fitting a new heat exchanger.

southcoastrgi

yes he will know it's called "kettleing" & is caused by scale build up in your heat exchanger, only two things you can do to stop it, fit a new heat exchanger or clean the inside of it with chemicals.

ilikewatch

[STRIKE]

alanobrien wrote: »

Some may suggest a powerflush but that can cost more than fitting a new heat exchanger.

And wouldn't actually remove any of the scale on the DHW side of the heat exchanger which is 99% likely to be the cause of the issue...[/STRIKE]

SplanK

Yes, water boiling in the matrix is actualy called "kettling" as it sounds like a boiling kettle! It cutting out is probably an over heat function kicking in to protect itself.

It could be a number of things, but if you explain it to him as you have above he should be able to investigate properly and come up with an answer.

southcoastrgi

ilikewatch wrote: »

And wouldn't actually remove any of the scale on the DHW side of the heat exchanger which is 99% likely to be the cause of the issue...

the OP has already said it's not a combi, therefore the heat exchanger will be the same for the heating & hot water, plus even if it was a combi by putting a descaling chemical through the boiler & turning on a tap this would descale the heating side of the plate heat exchanger, if the domestic side of a plate heat exchanger was scaled this would refect in the flow rate & temp of the water at the taps & wouldn't give the kettling that the OP has.

pinkteapot

Thanks all! I wanted to check as my husband thought I was going mad and that the boiler had always made that sound. It hadn't - it started a while back and stopped when I turned the water temperature down on it.

My brother's a plumber (not GasSafe though so he's not doing the servicing - he just does bathrooms now) and I've heard about what plumbers can charge for powerflushing!

EDIT: Just read about kettling online and it describes ours to a T. We live in a very hard water area so not surprising really. We also haven't had the boiler serviced since we bought the house two years ago, and not convinced the previous owners serviced it for a while before that.

southcoastrgi

servicing won't solve your problem, the correct level of inhibitor however would have.