low pressure in combi boiler

lollipop320

Our combi boiler keeps losing pressure but only when the nights are below freezing. It works ok during the day but if we have a cold night when there is a thick frost on the ground or snow the pressure drops overnight and the boiler does not start and we have no water. We top the pressure up and it continues to work corecctly for about 2 days then it we have anonther cold night the same happens.

I don't know what make it is and the boiler is on a timer to go off at night. It does have a saftey system when it comes on breifly during the night to stop freezing, which I have heard during the night but can't really remember if i hear it the nights when the pressure has fallen.

Any help would be greatfully received

Mr_Ted

Without full info on installation details its difficult, and will definately need a qualified person to inspect to ensure no installation problems and that everything is doing as it should do, especially the frost protection!

This is a pure speculation, but it could be that if the boiler fires on frost protection mode and it is not properly interlocked into the rest of the controls, that when the boiler fires the water is expanding due to the heat and overpressuring the boiler and you lose water via the safety valve!

As I say pure speculation, does the pressure remain as should be, approx 1 bar, under normal conditions?

More info required and definately an inspection!

nickcc

Firstly I'm not a heating engineer. In my opinion if the pressure on the gauge is constantly dropping and the heating system is free of air then I would expect there to be a leak somewhere in you're heating system. I had a new combi boiler last year and have occasionally had to top up the system but I would put this down to air being left in the system and being vented through the boiler air eliminator valve.

maintenanceman

Get your vessel checked

ButterflyBee

I must add my 6pennies worth as the same was happening to me since October last year and it was stressing me out to death.
Thanks to :money: I checked out the details of my 'upgraded' bank account it came to light that I was also covered for Home emergency cover. (I had no heating what so ever)

Well they sent a nice little boilerman and he very quickly re-pressurized the expansion vessel with a fancy bicycle pump!

No charge! :T

just a small observation......
Check to see if you are covered
probably only need to re-pressurize the expansion vessle

nickcc

We had an expansion vessel on our previous conventional heating system but not on our combi boiler. All the combi's I've previously owned just have a flexi hose with a valve on either end that allows you to top up with mains water.

diywhynot

lollipop320 wrote: »

.
I don't know what make it is

You need to post the make and model of your boiler.

lollipop320

Make Ferroli model Falcon II.

We do have emergency home cover with our bank account (I never thought to check this) so will check with bank.

Pressure does stay around 1 bar during normal use.

We don't appear to have any leaks we checked that and this problem only occurs during cold weather

Mr_Ted

Still suspect as per post 2 in that case?

southcoastrgi

nickcc wrote: »

We had an expansion vessel on our previous conventional heating system but not on our combi boiler

yes you have

nickcc

southcoastrgi wrote: »

yes you have

Where's it located, on the conventional system it was a largish red round cylinder which you could re charge but no such animal on our new Viesmann combi boiler.