Re: Sealed instead of vented heating system
Much of what Dextrous says is correct. However, after flushing and fitting a magnaclean, you should not need to flush again.
And yes, add an inhibitor.
However, you've not explained properly. Is it that the boiler itself is not working, or the heating is not working due to sludge in the rads??
Some notes:
1. Don't get ripped off with a powerflush. They will give all sorts of bull to justify the cost, such as the cost of the equipment etc. Truth is, a decent one is around £700, but they use it all the time and they last years. All you should realistically be paying is a days labour, plus a bit of travel time / mileage, for a decent reverse flush to be carried out. Plus the cost of a decent inhibitor like Fernox.
2. If you have a combi system fitted, as Dextrous said, you'll need a powerflush as part of the works anyway.
The increase in pressure should have no effect. Another scare tactic to extract more money from the unknowing. Still have an inhibitor added to the closed loop heating circuit though.
3. If you go the route of a high efficiency condensing combi, you should find that your heating bill will drop quite a lot. You also gain space, as you will lose the hot water cylinder and both tanks in the loft.