New boiler/power flush - am I being misled?

I know nothing at all about plumbing matters so please excuse my ignorance. I have recently had an Ideal boiler fitted by a registered plumber. First I obtained a quote which stated
Remove and disconnect the existing boiler from the kitchen cupboard.
Disconnect and remove the existing domestic hot water cylinder and the cold water storage tanks.

Make alterations to the pipe work and convert the system to a combination boiler system.
Supply and install a Viessmenn 100 35KW complete with a Vertical flue, vertical flue kit and a roof f slate.
Fill flush and clean the system pipe work and radiators.

However that plumber could not start for a while so I asked another registered plumber to quote on the same job having showed him the details in the above quote. He came back saying:-
ive had a look around and have come across an ideal independent 35kw (which is on par with the veissmann if not better and with a better hot water flow rate) with relevent flue parts, 2 x remote room thermostats/programmers, 2 zone valves to seperate heating circuits between properties.
After he had fitted the boiler the downstairs radiators did not come on at all. He said a power flush was needed however the previous owner of the property mentioned that there was a valve under the floor which needed turning on which the plumber would not know about. I think the heating is in 2 zones. This valve was turned on and the heating came on. I told the plumber this and he said that a power flush would still be needed. His comments were
As a qualified engineer i can only advise you that all of the system still needs to be flushed and cleaned properly as we could only do the 1st floor when we were there before, if there was any silt or dirt in the downstairs circuit this will now be flowing around the system and through the boiler and if anything does go wrong with the boiler and it is found to be the dirt that has contributed to the damage your boiler warranty will be void, and you would have to be paying out for spares and labour again so like i said i'm only advising you to get it done.
Until the downstairs radiators failed to work he had said nothing about a power flush - the only flush referred to was as mentioned in the quote above. I felt he should just come back and do with the downstairs radiators whatever he had done upstairs but he does not want to come back unless he can do this power flush.
1. Why would he not have thought it needed a power flush until the radiators downstairs failed to function?
2. On what basis would he decide it needed a power flush
3. If upstairs radiators were working but downstairs were not was it reasonable for him to say it needed a power flush
4. I have seen comments to the effect that if you have a new boiler the power flush should be done before fitting not after - is that correct?
5. Is he obliged to come back and flush the downstairs system (an ordinary flush?!) in accordance with the quote?
6. He mentioned that some of the thermostats on the radiators dont work and he has said that they should all be replaced as the others are likely to go soon - is it possible for him to say that. He said every thermostatic valve and lock shield valve will need to be replaced ?
Many thanks for any help anyone can give

This is a DIY forum, not a consumer complaints department.

He must be an idiot because he said "Ideal" are better than "Viessmann", they are certainly not.


Ideal have a long track record of makking crap boilers,

Turbo2
Minimiser
Response
Icos
Isar
Istor
Mexico He
Classic combi



Looks like you've been sold a dud.


Was the Ideal quote cheaper by any chance?

It is always advisable to powerflush and old system before you fit a new boiler, and the manufacturer's instructions and guarantee are likely to specify it.

I have no idea why he didn't include this in the original scope of work, but as the Viessmann is a much better boiler, and more expensive, it might be that he was offering a cheaper job at a cheaper price. Also the long Viessmann guarantee is dependent on it being fitted by a trained Viessmann installer (they provide the training free)

It is a pity you and he didn't comment on the old rad valves before he started work. Obviously it would have made the quote higher, and some customers like to see low quotes. If you did not already have a working heating sytem you and he might not have known they were not working until now, but this is the sort of thing a customer would normally be aware of.

I don't think that you can reasonably blame him for not knowing about your hidden valve, or expect him to absorb the cost of the extra work it causes..

A heating engineer who is not busy at this time of year? Was he recommended by a friend or neighbour?

'Fraid you're suffering because you're doing your research AFTER having the job done.
Having two quotes with very different "solutions" should have been a pointer to there being a lot of possibilities.

If the system doesn't work, for reasons he didn't discuss with you, then you certainly have grounds for a complaint. But we can't really help with that, beyond pointing out that all boiler installation instructions will have a clause saying that the system must be clean before the boiler's installed - have a look for it.

Power flushing can save loads of problems if done correctly. There is and association for power flushing now where you can get more answers on how and what.

My only comment is why didn't the installer check to make sure everything was working before he finished. How many good installers leave without checking all the radiators work properly after fitting a new boiler. Sounds to me your installer rides around on a horse shouting YEE HAA all the way to the bank with your money