Boiler loosing pressure no leak detected don't know where to turn

Nyala_44

I have a boiler under warrantee, and I must repressurize it a couple of times a week. The boiler engineers have been out several times and changed the heat exchange as well as serviced the boiler and they are convinced I have a leak. This has been going on for a year and a half and has no impact on my hot water just my heating. I have had out several leak detection companies who have checked everywhere and sprayed the sealant in the system, each time someone comes out it seems to improve for a bit longer. I was told to isolate the boiler as I was going away at the weekend with the instruction if the pressure fell when I turn it back on it is a leak if not it is the boiler. I returned turned on the boiler and the pressure went up. Nobody seems to know what this means now, and I am in between boiler engineers and leak experts both saying it is the other and I have just turned the heating off and wrap up warm.

tacpot12

If the pressure in your boiler went up, there is only two reasons for this that I can think of: 

1. You isolated the boiler at a time when the system was very cold, and when you un-isolated the boiler, the house was much warmer. (I'd only expect the pressure to increase a small amount if this is the cause and it should really decrease if you really have a leak). 

2. You isolated the boiler from the central heating system, but didn't isolate the boiler from the mains supply to the central heating system by disconnecting the filling loop. If the valve on the filling loop was allowing even a tiny amount of water past, it will have pressured the system. (I would expect a larger change of pressure if this is the cause, e.g. pressure went up to 3 bar).

I don't think the cause can be a leak between the cold water supply for Domestic Hot Water and the Central Heating system (if this is a Combi boiler) because this would pressurise the central heating section of the boiler and you would have seen this higher pressure before you un-isolated the boiler from the central heating system.

Has the expansion vessel been checked? These can leak.

Ultimately, your boiler installer should be liable to fix the problem. If you have home insurance, check to see if you have legal expenses cover. If you do, call the Legal helpline provided by your insurer for felp to hold the boiler installers to account to get to the bottom of the problem. The water must be going somewhere! 

ThisIsWeird

Nyala_44 said:

I have a boiler under warrantee, and I must repressurize it a couple of times a week. The boiler engineers have been out several times and changed the heat exchange as well as serviced the boiler and they are convinced I have a leak. This has been going on for a year and a half and has no impact on my hot water just my heating. I have had out several leak detection companies who have checked everywhere and sprayed the sealant in the system, each time someone comes out it seems to improve for a bit longer. I was told to isolate the boiler as I was going away at the weekend with the instruction if the pressure fell when I turn it back on it is a leak if not it is the boiler. I returned turned on the boiler and the pressure went up. Nobody seems to know what this means now, and I am in between boiler engineers and leak experts both saying it is the other and I have just turned the heating off and wrap up warm.

Some clarification, please.
Make and model of boiler?
What do you mean by 'no impact on the DHW, just CH'?
Explain, please, the exact process of you isolating the system, and exactly the sequence of actions when you returned.