Boiler losing pressure... advice

stek2008

Hi folks,

We bought a 1930's semi last year and paid a local plumber/gas man to install a combi boiler (previously it was a back boiler).

This was fitted in the loft and the existing rads and pipework were altered to convert it to a 'sealed' system which I gather is to do with current building regs/best practice.

The boiler is a Worcester Bosch 28l condensor, this is plumbed in the loft with a 'saniflo plus' pump feeding the cold water into the boiler as needed (for the hot water supply, or when using the key thing to top up the pressure on the heating).

Some 4-5 times in the year we've had it installed I've had to go up there and top up the pressure as it's dropped into the red and the heating has gotten really rubbish at heating up.
Today I had to do so again - but as I was allowing water into the boiler one of the 'rubber bungs' on the saniflo pump jumped up and water went everywhere until I replaced it.

Have two concerns - why would the saniflo thing pop open like that?
And is it very unusual for the boiler to need filling this many times a year? We have no evidence of a leak anywhere but it seems like a lot of pressure to be lost in a quarter or less...

Any experiences / advice to share?

Thanks in advance

Steve

Ectophile

I don't know about the Saniflo pump, but having to re-fill the system 4 to 5 times a year sounds a bit too often to me.

Check to see if there's water dripping from the overflow pipe from the pressure release valve as these can get stuck. This isn't the same as the condensate pipe, which is supposed to drip.

Check thoroughly around the boiler for damp patches or drips from the pipe joints (there are a lot of them in a gas boiler).

Check the ends of all the radiators for damp or weeping.

southcoastrgi

a few things, it doesn't have to be a sealed system at all but if you had a combi fitted then the central heating will normally be sealed, did the "plumber" do a flow & pressure test to see if a combi was suitable because it doesn't sound like it, that's one of the reasons i never fit a boiler in the roof because as you are finding out it's a pain, are you sure that the saniflo really is feeding the cold water supply to your boiler ? what is the exact model of the saniflo ? because you aren't allowed to pump the mains more than 12 ltrs/min & it doesn't sound like the correct pump to do that, pics of the install, boiler, pipework & the pump would help

stek2008

Spoken to the installer tonight who is going to check it all over later in the week. He mentioned on the phone that I may be over filling the system (I've been taking it to the top end of the 'green' [around 2 bar]) and that could be causing some of the problems...

Evidently the Saniflo Plus pump is actually to get any waste water from the boiler out to the drain - does that make more sense?

When the system was redone it was pressure tested and also power flushed before the boiler was installed. No obvious leaks and the saniflo pump itself is no longer leaking since I pushed the rubber sea back in.

southcoastrgi wrote: »

a few things, it doesn't have to be a sealed system at all but if you had a combi fitted then the central heating will normally be sealed, did the "plumber" do a flow & pressure test to see if a combi was suitable because it doesn't sound like it, that's one of the reasons i never fit a boiler in the roof because as you are finding out it's a pain, are you sure that the saniflo really is feeding the cold water supply to your boiler ? what is the exact model of the saniflo ? because you aren't allowed to pump the mains more than 12 ltrs/min & it doesn't sound like the correct pump to do that, pics of the install, boiler, pipework & the pump would help

BertieUK

Spoken to the installer tonight who is going to check it all over later in the week. He mentioned on the phone that I may be over filling the system (I've been taking it to the top end of the 'green' [around 2 bar]) and that could be causing some of the problems...

I would say that you have found one of the problems, I have always kept our system, that is similar to yours, filling it with a setting no greater setting than 1 bar.

Regards
Bob

southcoastrgi

yes he could be right you should only re-pressurise it to 1 bar or just over when the boiler isn't working, the water will expand when it is heated pushing the gauge up & if the pressure goes over 3 bar then the prv will open draining the excess pressure to the outside, these valves can get dirt on the seating which stops them from closing properly & if this is the case then water will continue to go outside until all the pressure has gone & you need to re-fill it, yes the pump sounds like the condense pump which will take the condense from the boiler & pump it away, i'm surprised you need one in the roof as the condense pipe could normally be routed straight into a drain/soil stack without a pump

terakris

Our boiler was recently loosing pressure, i checked for leaks and couldnt see any... what i did was put 1 sheet of kitchen roll around each of the radiator pipes and left it for a day. When i returned from work, sure enough one of the tissues was soaked... so although the water was dripping slow enough to just evaporate in the carpet, it was causing a pressure loss.

Worth a try to at least eliminate the radiator valves as the problem.