Boiler has been loosing pressure for some time requiring topping up say once a week. Now pressure builds up to 3.5 bar and then ejects excess water through overflow. will repair be an option or is it best to replace. If so what is equivalent option for use in this two bedroom semi. What would relevant costs be.

A Wiggin, July 2007

Why do you have pressure set at 3.5 bar?

For a semi you only need 1 or 1 and half bar.

The system is designed to release pressure if it exceeds 3 bar, to prevent damage to pipework, boiler, rads etc..

If it is losing pressure, it means there is likely a leak somewhere? Any damp spots in ceiling? Otherwise, maybe under floor?

Pressure [approx 1 bar], should be set cold, as the water heats up it will increase pressure but should not cause release valve to open unless there is a serious fault.

Hope this helps?

brian, July 2007

to cure this problem with presure going up when heating on empty boiler,via presure release valve (as already leaking anyway,normaly you would not use this valve as it may not reseat correctly and continue dripping) and reprime expansion vessel this is at rear of boiler and can be re presurised with air via a car tyre pump to about 1 bar,replace presure release valve and refill
change the boiler by all means however the problems you now have with the puma are caused by a problem that will also affect any new boiler,in fact worse with the new condensate boilers and that is you have a leak in the system somewere which is why you topped up every week this could be on a radiator,valves or connecting pipework
if you top up every week not only are you putting fresh water in system put also helping fresh corrosion in system.on your puma there should be chemicals to combat corrosion ect however these boiler can last a while without ,this is not the case with new boilers and if you continue the top up every week ,and have no chemicals to protect new boiler its life could be as short as 18 months
So get system in good order before you replace,reprime expansion vessel and replace presure release valve on boiler,find and repair leak,if you cannot find ,as leak only small as last resort use a system leak sealer,get system sound
then as you have be topping up every week you will find corrosion ,black water in system this has to be removed for new boiler instalation add mild cleaning chemicals and let system run a few weeks,then flush out debre
once above done your existing boiler will be working so you probably will not replace yet but when you do the change over should be smooth and the new boiler content in its surrounding ;-]
ps as the puma is a very long boiler therefore all replacement boiers out there will fit and I hate to say it and I have not said for many a year now but the potterton (performer) or I think they have just changed the name of it to mains combi is a very good boiler mainly because its now owned by baxi,
However lots of good boilers out the just try to stay with the condensate boilers with old fashioned burner layout as cheaper to repair and longer life

tony...tsp heating, July 2007

filling loop was letting water through but was then closed fully.Pressure was released from system and when heating was then switched on pressure started at just over 1 bar and then climbed to 3.5 bar within half an hour.when system was then switched off pressure fell back to less than 2 bar in about the same time. overflow was now only slowly loosing water ( a slow drip ) above the 3 bar mark. Thanks for your help so far. A Wiggin ps what would be an equivalent boiler now.

A Wiggin, July 2007

>Boiler has been loosing pressure for some time requiring topping up say once a week.

leak in system somewhere check all rad valves, pipe joins, etc

>Now pressure builds up to 3.5 bar and then ejects excess water through overflow


have you shut filling loop fully, or is it now faulty wher it been open and shut a few times.

hi-spec plumbing, July 2007