Central heating pressure

[Yashokumar]

Hi
I am in a bit of a quandry and would appreciate advice regarding the pressure setting. I have an IDEAL CLASSIC NF60 boiler with a flexicon 8 attached. Its labbeled as a fanned flue gas boiler.
I used to have the boiler serviced annually by a plumber, and he used to say that it should that the pressure should be between 1-2, however he sadly had a stroke and retired. I therfere had called in a new chap, he claims the pressure setting was too high and that it should be below 0.5 when switched off (ie heating not on) and less than 1.0 when on. He also said that Since I had topped up the boiler I needed to put in an anticorossive retardant top up. He said that for him to do it he would need to drain the system and it would cost me around 300 + VAT depending on how long it took him to drain the system. I called up my old plumber and he said that this guy was incorrect, and that if I needed to top up anticorrosive all I had to do was isolate a room radiator and remove 1- 11/2 pints out and top it up, the way he described it seemed easy enough. I went to B&Q today and got the anticorrosive with a pump and tubes. When i tried to pass the tube into the room radiator a kind of T junction prevents me from being able to push in the tube. Unfortunately Peter ( my old plumber) is off on holiday to visit his daughter in OZ.
Any help and advice would be appreciated. Incidentally is it worth signing up with one of the Scottish gas etc plumbing insurance covers?
Thanks
Yash

 

[corgiman]

get covered, 300 quid to put inhibiter in your system is outrageous!

 

[Yashokumar]

Thanks for the advice. Yes I have bought the homecare cover... works out a lot cheaper. Still waiting for them to tell me what the ideal pressure should be..
Cheers

 

[Agile]

Most pressurised systems work best at about 1.5 Bar when cold.

Old Vaillant Sine 18 T3 boilers are better at 1.2 Bar.

Tony

 

[John2512_00]

You wont need to add inhibitor every time you top up the pressure as its likely the systems will only loose a little at a time when you need to top it up.

300 quid is a discrace for something like that, as its a straight forward job and You should be able to remove a plug on one of the radiators once the radiator is isolated.

Id stick with between 1 and 2 bar for the pressure, expecting it to be closer to 1 when cold. If in any doubt Then the manufacturers instructions will tell oyu where to keep it. It doesnt make much difference as long as it doesnt run much under a bar or up near 2.5-3

 

[Yashokumar]

Dear Agile and John
Thank you for your advice. I am not much use at DIY and made the mistake of telling this to the guy. I don't know whether he was trying a fast one or not. His explanation for the charge seemed plausible (or I am gullible!) he said he had to drain the system to When I had bled one of the radiators it had come out as black stuff, so he felt that the system had to be drained out be able to add inhibitor and expected the job to take 5-6 hrs and as his rates were 60/ per hour had given a ball park figure with a little flexibility depending on the time needed.
Thanks for the advice regarding the pressure levels.
Cheers

 

[meldrew's_mate]

.... When I had bled one of the radiators it had come out as black stuff, so he felt that the system had to be drained out be able to add inhibitor and expected the job to take 5-6 hrs and as his rates were 60/ per hour had given a ball park figure with a little flexibility depending on the time needed....

It sounds like your new guy had identified some remedial work based on the sample of black water coming out of your system. This means that you have contaminants in the heating which need to be removed (drained). Typically this will entail adding a flushing chemical a couple of days before draining the entire system, refilling & redraining, then filling and adding a protective chemical (inhibitor). Perhaps that explains the higher cost

As for the system pressure, it all depends on the no. of storeys the heating has to service, in general 0.5 bar + (no. of storeys)x0.3, so for a typical house only 1 bar when cold. Higher pressures give no advantages at all, as long as the highest point is under positive pressure it'll work fine.

 

[Yashokumar]

Thank you. I do feel that the chap seemed to know what he was talking about.
Cheers mate