Boiler problem

bouicca21

I had my boiler Greenstar 25si serviced in the summer. Last week I had a Nest thermostat fitted. A few days later the pressure had fallen back. I re-pressurised it.

Thermostat set to Eco overnight (9degrees). Today, funny noises. Checked and pressure = 0. Repressurised, pressure immediately fell back. Repeat, pressure fell back.

Do I have a massive leak somewhere? Boiler on the blink? Something to do with the Nest? Massive bill in the offing? The boiler is Probably nearly 5 years old.

I doubt I can get a heating engineer out at the weekend without paying some kind of surcharge. I can cope with the cold for a day or two.

tacpot12

Very unlikely to do with Nest. There is a leak somewhere.

I would spend the time between now and when the plumber comes trying to find the leak, as this will reduce the cost of the plumber. Starting looking anywhere where there has been work done recently. It is possible that the Nest thermostat has been screwed to a wall, and the screw has hit a heating pipe buried in the wall. Check the radiators and all the visible pipework first.

nofoollikeold

You should have a 15mm copper pipe going to the outside of the property, normally very close to the boiler. This pipe, which should be directed back towards an outside wall at its exterior end, is to take any flow of water due to excess pressure away safely. Excess pressure causes a valve inside the boiler (the Pressure Relief Valve (PRV)) to open. Once they have been opened they have a tendency not to re-seal.

Re-pressurise the boiler and see if water is dripping from the copper pipe. Don't confuse it with the white plastic pipe which may also go outside. If water is dripping you will need to get the PRV replaced by a gas safe registered engineer.

bouicca21

Ta. The pipe work is under the floor. I can't see any signs of a leak but if it is sloshing round under the floor it might take a while to be noticeable. I can't see any evidence of a discharge outside either. The loss of pressure is instant so any leak must be massive.

The blue on/off light on the boiler is on but the burner light is not. The pipe work to the boiler is visible behind a housing so I don't think there are any pipes in the wall that could have been affected by the placing of the Nest receiver.

I did have a slow leak about 18 months ago. The entire floor was taken up and the pipe work checked. The thought of going through all that again is mega depressing, especially as there was a ginormous bill. The insurance paid out then but might quibble about doing it again.

bouicca21

When it is repressurised the burner light comes on, then goes off as the pressure drops.

bouicca21

No water going via overflow pipe, but although the heating has been off for some 14 hours (I Set it to Eco at about 11 last night) the condensate pipe is wet. Could the water somehow discharge down the condensate pipe?

bris

If no water is present anywhere that you can see then you may have a leak at the heat exchanger which is going down the condensate pipe.


That's the 21mm white plastic pipe that comes from under the boiler. Fill the system and see if you can hear anything running down that.


Just seen the above post. The condensate pipe shouldn't be wet on the outside anyway as it's supposed to be sealed but yes it could be an indication your heat exchanger has split.

bouicca21

I think I've misled you. I meant that there is (or was when I checked it earlier today) a liquid discharge from the condensate pipe even though the boiler had not been working for 14+ hours. The copper overflow pipe is dry.

Am I right in thinking this may mean that the boiler itself is faulty rather than there being a leak in the pipework? The boiler was serviced in July so I didn't expect it to go wrong for Christmas.

Alex1983

You could have a boiler serviced a week ago it doesn't mean it won't go wrong today. A boiler service in July has nothing to do with your problem today.