Intergas RF36 losing pressure!!
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Doesn’t present as an Intergas specific problem — most likely a general boiler issue.
First thing I’d check is how much the system pressure rises when all the radiators are fully hot.
Difficult to give an exact pressure difference because system size and setup varies, but in general there should be no more than a one bar rise in pressure between cold and hot.
As an example, my boiler (Intergas Xtreme 30) When every radiator is fully hot, the pressure only increases by about half a bar above its one point two bar cold pressure. But, it is not a big system. Just five large radiators and two towel rails.
If there is too much of a pressure rise when hot, you might want to have the boiler’s expansion vessel checked. It could need pumping up or the vessel may have failed.
The purpose of the expansion vessel is to absorb pressure increase caused by expansion of the water when the system is hot. If the vessel is not performing this function properly the boiler’s pressure relief valve may have to dump water to reduce pressure for safety reasons.
Also, since you mention having extra radiators installed, it may also be that the built in expansion vessel in the boiler is no longer big enough to deal with the larger system.
If that is the case a competent installer should have compensated for this at the time the extra radiators were added by fitting an additional external expansion vessel though.
If the expansion vessel was not working properly and then you later added more radiators, that would give similar symptoms to those you describe.
Expansion vessel(s) must be checked and if need be, pumped up at every annual service if the service is being properly done.
Your boiler is pretty new and proper functioning of the expansion vessel should have been verified during boiler installation and again during its last annual service, but it is definitely still worth checking.
There are other causes of your issue, but the expansion vessel would certainly be the first thing that I would eliminate as a cause before looking at anything else.
Related: It’s good that you are looking into this. Every time the boiler needs to be topped up with mains water, the corrosion inhibitor in the system is further diluted. In addition, more oxygen is introduced into the system. Not good.
Water quality is everything in a hydronic heating system. If corrosion is allowed to develop, lots of bad (and expensive) things happen. It’s all downhill from that point. One of the many things that can happen as a result of corrosion is a leaky pressure relief valve.
Until this issue is resolved, you may want to add some inhibitor from time to time. It’s fairly cheap.
In fact, if you have had to top up the system every day for some time now, you should probably add an entire bottle of inhibitor immediately.
Good luck — it might well be a straightforward issue.
Regarding your choice of an Intergas boiler, my experience of them is that they are of well above average quality. Excellent boilers, but like every boiler they need to be properly installed and serviced.
Originally Posted by franc0nelis
