Vaillant Combi boiler 242

On my boiler, the domestic hot water has got cooler lately, although the thermostat is turned up. I think the DHW heat exchanger needs replacing, it has been done some years ago. I assume, these become furred-up from hard water. Is it possible to soak them in large volumes of kettle de-scaler and then re-use them? I never thought of this before. any advice appreciated thankyou.

On my boiler, the domestic hot water has got cooler lately, although the thermostat is turned up. I think the DHW heat exchanger needs replacing, it has been done some years ago. I assume, these become furred-up from hard water. Is it possible to soak them in large volumes of kettle de-scaler and then re-use them? I never thought of this before. any advice appreciated thankyou.

Circulating a solution of Fernox DS3 through the fresh water side should do it.

Yes that is possible, although we just bought a new heat exchanger, couldn't be bothered with the faff of descaling while the boiler was in bits, and now we've got a spare :o)

Now we don't need the water temp dial set beyond halfway...

The interesting thing was how much heavier the old heat exchanger was compared to the new one. I could feel the difference in my hand...

If you do buy a new one watch out, there are different variants depending on the age/revision of your boiler.

The very first ones didn't use a plate heat exchanger at all. The newer ones use one of two designs, part numbers 065088 is the larger long 12-plate one and 065131 is the smaller coffin-shaped (tapered corners) 40 plate one.

Suggested technique? (Or do you mean, after removing the HX?)

Yup, sorry should have made that clear. Remove the HX, and arrange some way of pouring/pumping the descaler through it.

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D\

=A0 =A0 =A0 =A0|

=A0 =A0 =A0 =A0|

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D/

Now have quote from plumber of =A3130 (inc VAT) for new HX, plus fitting. I was a bit startled at the cost, but not much I can do really. Will keep the old HX, try to de-scale it. Plumber also mentioned could be fault in PCB, and these are =A3200 it seems. He suggested, if it is the PCB, following fitting of new HX, to replace the boiler. This combi is only 11 years old, are they all prone to faults? My original vented system gas CF boiler was in use for about 25 years, until it leaked. Seems these new boilers are good for plumbers profits!

Well other than descale the one you have. I don't know what the price of the HE is, but when added to call out charge, and time etc £100 does not seem to surprising.

See

Well any can have faults - but to an extent you get what you pay for. Valliant are fairly decent and should be serviceable for longer.

Modern boilers are significantly more sophisticated - so in a sense there are more things that can go wrong. Cheaper ones can have worryingly short life spans, but reasonable ones should still last well. They ought to save more than their cost in gas within their lifetime as well in many cases.

Well ripping and replacing basically working or repairable combis is a stock in trade for some plumbers!

In message ,

A plumber who can'r differentiate between a heat exchanger and a pcb fault shouldn't be let anywhere near a boiler

The expected lifetime of a modern boiler is 7 years (i.e just long enough to be "fit for purpose")

In article , 4square writes

In my (albeit limited) experience, combis are a waste of time unless you have an electric shower and have one rated about 3 times what they say on the tin!

In message ,

No, I think you are missing the bleeding obvious there

In message , John writes

It has less to do with it being a combi than just a modern boiler

You said it, "limited". Buy yourself a proper, quality, correctly sized combi and install an in-line instant electic heater for the shower as backup, which can also do a tap as well.

Look at an ATAG 51kW, W-Bosch HighFlow 550, Broag 39C.

There is Fernox decaler available from B&Q.

Maxie, can you point to some figures about this 7 years, or did you just make that up?

In message , Doctor Drivel writes

I have seen the figure quoted in several trade mags

Prolly not in the manufacturers brochures you use (for some reason)

Drivel is blowing it out of his bottom, again.

"Modern condensing boilers, by contrast, have lightweight aluminium alloy heat exchangers and are heavily dependent on electronic control systems, which have a limited life. It was recently reported in an engineering journal that modern condensing boilers have a life expectancy of five years. Whereas your existing boiler - given a reasonable degree of care and maintenance - might last another 25 years."