Boiler prob.

20 Jan 2013
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United Kingdom
I have had a new boiler fitted December.
It is a Grant Vortex 26 combi internal.
It has replaced a Grant Vortex 26 combi external. The old boiler was 4 years old and serviced a system of 10 rads - not known how old the system is, I have acquired the central heating when buying the property 20 months ago.
There has been no change to the system other than replacing the boiler.
I had no problems with the old system/boiler.
Since the new was fitted I have been losing pressure to the extent that now I am refilling once a day to one bar.
Have checked system for leaks - nothing found.
Grant said it might need another expansion vessel.

Has anyone experienced similar or has any idea what problem is? Help!
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Get the installer back!

Why did you replace a boiler which was only 4 years old??
The installer was back this morning. He spoke with Grant as well - from the words used after that phone call, I got the impression he thought he was being fobbed off.

I replaced the boiler after renovating a utility area and I am now able to use residual heat (such as it is, and it does a job) inside. Not much of a reason admittedly, but it is the only one I've got (and no, I am not loaded)!!!!
put a balloon or a small plastic bag over the end of your pressure releif valve outlet and if water gathers in there then it would point to an expansion vessel problem or a faulty PRV, if no water and the pressure is still dropping it is something else
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It is a leak.

Either from the expansion vessel or from some internal pipework.

If Grant use Zilmet expansion vessels then failure is very likely, we have been refusing to fit these recently due to the number of failures.

If your new boiler had been a Worcester-Bosch, your installer would find them willing to come out without an argument. That's the main reason why we don't use Grant as a first choice anymore.
Thanks for those replies.
I now have a plastic bag wrapped over the PRV outlet - time will tell.

As an additional point - while the central heating is working, ie: pumping the hot water round, pressure remains constant (as far as I can tell) and it is not until I switch the heating off that the pressure gradually drops.
I would have thought that pressure would drop as heating was working???

When the heating is on, the pressure will rise due to the water in the (supposedly) sealed system expanding.

If it isn't rising when the temperature is increasing you are losing water quicker than you thought.
The pressure does rise when heating on - I appreciate the expansion happening - but I thought that there would be a gradual fall in that pressure as the water was being pumped round.
In other words, why does it appear to only lose pressure after system is turned off?


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