Mains pressure min. required for indirect, unvented system?

[elemoine]

Sorry, but I haven't been able to find a post that answers any of these questions.
My flat is 9 years old, on 4th floor. When built, unexpectedly the mains pressure was deemed insufficient for the needs of the C/H system. Booster pumps were hastily installed at the last minute for all flats above 2nd floor.
My pump has failed and as a temporary measure, a plumber without specialist knowledge has bypassed it, so now I have water at 'mains pressure'. I can't get a specialist to look at the pump until Monday.
Q1: will it damage the C/H to be supplied with water below its required pressure? If so, should I take measures to preserve C/H from damage, i.e., switch it off?
Q2: how do I determine what pressure it is that the C/H requires and what pressure is currently being supplied unboosted, direct from the mains?
Q3: the bypassed water pressure coming out of kitchen tap now doesn't appear that different from previously boosted pressure. Is it possible in the intervening 9 years that Thames Water has improved the mains pressure sufficiently that I no longer require the booster pump?

 

[ianmcd]

what is the make and model of your boiler ?

 

[ChrisR]

Q1 no damage, but you might have trouble topping it up, which you may only need to do very infrequently
Q2 if you need to top it up and can't, then you have insufficient pressure
Q3 Just possible, yes. It will probably be lowest at showering time in the a.m. and may depend a lot on others' use within the bulding. Middle of the day or night may be fine.

I'm making some assumptions about your level of understanding of your system. They, or your understanding, may be faulty! There's usually something else which has a bearing...

 

[elemoine]

Hello ianmcd, Sorry I should have said the boiler is Potterton Suprima 40L. The tank is Harton Cosybug.

Hello ChrisR, my level of understanding of my system is low, but getting a higher day by day, as it's been a lot of trouble lately! When you say 'topping it up' I have visions of pouring jugs of water somehwere, but I am sure that's not what you mean. How would I 'top it up'?

Thank you both for your replies, and to this forum generally for easing worry and helping to increase my understanding. Many thanks.