Radiators not piping hot last year

w00519773

Last year in winter; I noticed my radiators were not piping hot when the central heating was on. Therefore I maxed out the thermostat and left it all day. Still the radiators were only warm.

I called a boiler engineer who has advised replacing the boiler. I currently have a Potterton Powermax 85HE CP. I believe it was installed when my house was built in 2002 (I moved in; in 2013) though Potterton seem to think it is more like 2007 due to the serial number. The boiler engineer has quoted circa £3K to replace my current boiler with a Worcester 4000 30KW.

I own a 3 bed (2 floors) semi detached house with a main bathroom; an ensuite and a WC. It also has a kitchen, lounge and dining room. I have two questions:

1) Is £3,179 reasonable (I have never had a boiler replaced before)? I have no idea whether this is a good price or not. I live in Lincolnshire.
2) Is the 4000 sufficient for my house or should I be looking at the Worcester 8000 35kw boiler, which was also quoted (at £3,679)

I live alone, however I am conscious that I may sell the house one day and a family may move in who have more requirements than I do e.g. multiple people requiring hot water.

They have also said they will perform a system cleanse using an inhibitor. Another company suggested a power flush for the radiators.

Albermarle

18 years is usually when things start to go wrong and maybe it is time for replacement.
However did the boiler engineer actually say what the problem was ?
Probably by shopping around you could it a bit cheaper but not by that much.
30KW should be enough for a 3 bed semi , with limited hot water outlets.

Vitor

- Another company suggested a power flush for the radiators. - 

IMHO to get the maximum guarantee on a Worcester Bosch install requires a power flush and installation of a magnetic filter.

Zekko

Is it all the radiators in the house that are not getting up to temperature, or just some of them?
Do you have cold radiators downstairs and hot radiators upstairs?

Check the TRVs are set correctly. You can also check if the TRV pin is stuck (lots of guides of YouTube).

If the radiators are much warmer at the bottom than the top then it’s likely trapped air. Bleed the radiator.

If the radiators are much warmer at the top than the bottom this can indicate sludge or debris block the flow of water. A power flush would help in this case.

I would get a different heating engineer to double check your system.

WIAWSNB

You won't need the 35kW in order to heat your home - your CH will draw a lot less than this - but the extra 5kW over the 30kW will give you noticeably better showers and faster bath fills, if that's important? 

However, you will need a matching cold water mains supply in order to benefit. Any idea what your mains flow and pressure are like?

Hang on - is your Potterton one of these large floor-mounted jobbies with a built-in unvented hot cylinder? And the WB replacement is a straight forward combi? If so, then the WB combi will almost certainly be a 'flow' disappointment compared to the Pottie, as it has to heat the water instantly on demand. If that is the case, then I'd suggest the 35kW. 

Rodders53

Potterton Powermax HE 85 CP Gas - Boiler Efficiency Rating suggests it is a condensing combi boiler and Promax Review is a scathing view of them by one Gas installer showing a wall mount version (and cast iron heat exchanger).

Get at least another two opinions/quotes for a new boiler install.
 
Consider a ASHP install (will need unvented HW tank installed) for the Grant money if you have space?

twopenny

Don't think ahead to what someone else might or might not want.
That's gambling 
They will choose for themselves and it won't affect a house sale. I sold mine for the asking price with no boiler or heating.

Choose what is right for you now.

A power flush helps a lot. I had that done for £100+ done in an hour or two. It's the same thing as the 'system cleanse ' .
The inhibitor is a fluid when they refil the radiators and it stops any internal rust. They should ensure the filter is cleaned or replaced.

Someone will confirm but you could try that first. I doubt it would be cheaper as part of the boiler installation.

When I say first, after you find you've checked what Zekko said about which and where the rads are getting hot or cold.

w00519773

Albermarle said:

18 years is usually when things start to go wrong and maybe it is time for replacement.
However did the boiler engineer actually say what the problem was ?
Probably by shopping around you could it a bit cheaper but not by that much.
30KW should be enough for a 3 bed semi , with limited hot water outlets.

I had a plan with Baxi for many years. It originally costed £17 PCM but increased to £85 PCM over the years because of the age of the boiler. I cancelled it earlier this year because Baxi said they could not help with the radiators as it was down to sludge.

The two engineers who visited both said a new boiler should resolve the sludge issue:

1) The first said a power flush should resolve it (included with their quote).
2) The second said a system cleanse using an inhibitor should resolve it (included with their quote).

w00519773

twopenny said:

Don't think ahead to what someone else might or might not want.
That's gambling 
They will choose for themselves and it won't affect a house sale. I sold mine for the asking price with no boiler or heating.

Choose what is right for you now.

A power flush helps a lot. I had that done for £100+ done in an hour or two. It's the same thing as the 'system cleanse ' .
The inhibitor is a fluid when they refil the radiators and it stops any internal rust. They should ensure the filter is cleaned or replaced.

Someone will confirm but you could try that first. I doubt it would be cheaper as part of the boiler installation.

When I say first, after you find you've checked what Zekko said about which and where the rads are getting hot or cold.

That is interesting.  The company who offered the powerflush implied that this is superior to a system cleanse?  The company who offered the system cleanse have replaced two boilers on my road over the last six months and both customers were pleased with the work so i would rather use them on that basis.

WIAWSNB

WIAWSNB said:

You won't need the 35kW in order to heat your home - your CH will draw a lot less than this - but the extra 5kW over the 30kW will give you noticeably better showers and faster bath fills, if that's important? 

However, you will need a matching cold water mains supply in order to benefit. Any idea what your mains flow and pressure are like?

Hang on - is your Potterton one of these large floor-mounted jobbies with a built-in unvented hot cylinder? And the WB replacement is a straight forward combi? If so, then the WB combi will almost certainly be a 'flow' disappointment compared to the Pottie, as it has to heat the water instantly on demand. If that is the case, then I'd suggest the 35kW. 

Could you answer the info required, please?

WIAWSNB

w00519773 said:

That is interesting.  The company who offered the powerflush implied that this is superior to a system cleanse?
  
YES, in general, but it depends on the detail.

The company who offered the system cleanse have replaced two boilers on my road over the last six months and both customers were pleased with the work so i would rather use them on that basis.

AIui, a 'powerflush' involves connecting your radiator circuit to a pumped flushing device, and uses strong cleaning chemicals forced around your system to shift the sludge. This is usually accompanied by each radiator being agitated using a vibrating tool, which loosens the compacted sludge which will have formed at their lowest points. A large magnetic filter catches this sludge as it's put into solution. So, yes, usually a very thorough process.
A 'system cleanse' involves adding cleaners to your CH system, and the boiler is run as normal. A small magnetic filter might first be plumbed in - one will be required as part of the new installation in any case - but usually the sludgy water is just drained away, and refilled. At its most basic, this is not thorough, as some sludge will almost certainly be compacted inside the rads, and be very hard for just chemicals to shift.
I guess there will be variations of each type which will govern their effectiveness, but in general a 'powerflush' is far superior. And if you know that there is significant sludge in your system, then I know which one I'd go for.
As said, 'inhibitor' is a system corrosion preventer which is added after the cleaning has been done, and should stop any further corrosion. But it ain't a cleaner. I suspect you may have misheard the guy as he explained what a 'system cleanse' was, and latched on to that 'inhibitor' term?
As a layperson having a new boiler fitted, you shouldn't have to know all this. It should be enough to know that each new installation must be cleaned to a BS, and a magnetic filter fitted. Then, provided you have the fairly costly annual services carried out, your new boiler should be warranted for a decade or so. Any issues down to remaining sludge 'should', therefore, also be covered, in theory.
If you want to make a decision based on flush quality, then you'd need to know exactly what each installer would do, as these 'powerflush' and 'system cleanse' expressions are bandied about and have flexible meaning unless defined.
Or, if you will be having annual services from an authorised WB agent in any case, you can just act the layman and let the 'contract' look after you :-)