wocester bosch boiler

5 Jan 2010
Reaction score
United Kingdom
Central heating upstairs works fine but downstairs fluctuates-but mostly cold, even when stat temperature has not reached setting.
I turned the radiator valves off upstairs and the downstairs heated up.
I then opened the radiator valves upstairs and all worked, but noticed same happened after hot water for shower used (Maybe a coincidence?).
Boiler pressure is 1.2 bar-(recommended in wocester bosch highflow manual is 1.5 bar) but when I open water inlet to boiler to increase pressure all that happens is hot water release from boiler overflow. I use to be able to increase pressure up to 1.9 bar until recently but pressure has dropped to 1.2 over a period of about 5 weeks. Any expert advice would be appreciated!
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I think you need a competent boiler engineer.

Balancing, pump, EXV, PRV etc., you have a lot of possibilities.

Boiler repairs are not easy and need a very competent person to properly assess the situation.

Thanks for that Tony. Since posting I have talked to a heating engineer who suggested checking pump by unscewing centre nut and inserting scewdriver to see if pump is acually running. He thinks symptoms suggest that pump needs replacing. What do you think?
I think its running but may be blocked or running slow.

See FAQ on "finger test" if you want to test it properly yourself.

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Hi Tony, how would I know if it blocked or running slow and how do I find the 'Finger test' I am new to the forum so would appreciate some help?

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