Boiler pressure over 3 bar

[joun]

Hi there,

I've been having high boiler pressure (between 2.5 to 3.5 bars) for over a week now. We had a plumber come in a couple of days ago who drained the central heating circuit, added two bottles of inhibitor and filled it back up so that the boiler showed 1 bar pressure.

We have left the filling loop disconnected, so high pressure definitely isn't because of that. The plumber said we might need to get another expansion vessel outside the boiler to accomodate for the volume of the system.

So the next day the pressure was back at 2.5 bars, and now I'm also getting the smell of the inhibitor in our domestic hot water! I can't smell the inhibitor in cold water from the tap, but the smell is definitely in the hot tap water.

Can't work out how the inhibitor from the CH circuit would get into the domestic hot water or why the pressure is that high - I thought the heating circuit is meant to be sealed? Could there be a leak between our CH circuit and mains water or the megaflo?

So I'm a bit worried about the high pressure (3.5 bars when the boiler is on), and the potential health hazard of inhibitor in our bath water.

As it's NYE it'll be pretty hard to get a plumber in this weekend, anything I can do in the meanwhile? Is the boiler safe to leave on if the pressure gets to 3.5 bar?

We've got the following:

Boiler: Greenstar 30CDi system boiler
Hot water tank: 210 litre unvented indirect Megaflo tank

As I understand the central heating loop runs inside a coil through the megaflo to heat up the domestic water in the tank.

Many thanks for any suggestions and happy New Year to all the forum members!

Joun,
London SW19

 

[muggles]

Are you able to isolate the cylinder from the rest of the system? My immediate thought is that the coil in the cylinder has split. How old is it? It's probably in warranty, in which case Heatteam would be the people to call

 

[joun]

OK, how would I isolate the cylinder from the rest of the system?

The megaflo and the boiler are both just over 1 year - that should fall within warranty, right?

This might be completely unrelated, but something that also came to mind is that the contractor who originally did our plumbing about 18 months ago had the mains cold water and CH flow pipes connected, with a diverter valve in between, to test for leaks initially, I think.
I always thought it was a bit dodgy to leave the two connected - the valve was left closed after the job was finished but I thought it could start leaking between the two pipes later. Not sure if that's related in any way though to the issue we have now

 

[muggles]

If that link's been left in it could be that. If it's a true Megaflo it'll have a 20-year warranty, assuming it was correctly commissioned of course

 

[joun]

Good to know. Genuine Megaflo, that and boiler was installed by a gas safe registered plumber with 20 years experience, should be correctly commisioned - I hope!

A bit worried about the pressure going over 3 bars, for the next two days before I can get anyone in, is it advisable to turn the boiler off completely or at least bleed some water off a radiator to get the pressure down?

 

[flameport]

had the mains cold water and CH flow pipes connected, with a diverter valve in between, to test for leaks initially, I think.
I always thought it was a bit dodgy to leave the two connected

Dodgy is right.
Have the valve completely removed, as this is very likely to be the problem, and even if it isn't, the valve should not be there.