Troublesome old heating system

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Hi all,
apologies for the non descriptive header - but can't really think of a better way as this a question with so many facets!

I'd really appreciate some advice from those who know on my current situation.

My wife and I moved house September last year. When we moved, we knew that the central heating system was old and would need replacing sooner rather than later. We felt it needed replacing partly because of it's age and inefficiency and partly because the previous owner has made it ridiculously over complicated.

What we currently have is a Potterton Kingfisher 2 - 23.5 Kw. Around 20+ years old. This is split into three "zones" controlled by Honeywell CM61NG wireless controllers. Without question, the system could do with a powerflush - we have lots of hot spot problems on the rads and it takes an age to heat up. And certainly our first winter has shown that efficiency wise, we need to do something - the boiler is constantly (and I really do mean constantly) on and our gas bills are ....err...interesting. To add fuel to the fire, the controllers are mad. They don't seem to do what you want at all....the heating comes on when it wants, it won't come on if you want it to and some radiators will heat up when others (in the same zone!) won't.

So. Clearly a need to replace longer term - but we had decided initially to hold off as we hope to extend in a year or two and would like to relocate the central heating if we do.

However, last week, whilst running a bath for my year old daughter, the hot water failed. At the same time, the central heating has failed for all three zones - although there is SOME heat going to one of the zones. We had a plumber round yesterday who didn't really seem confident of the answer, but suggested a powerflush - £400 cash for approx 12 rad system. He confirmed the pump was still working and the controllers for the fly by wire units are also still ok.

Given the lack of confidence he's given us, this caused us to question - and here is where I'd appreciate knowledgable input.
A) We had been told previously you are not allowed to re-locate a boiler now. I.e. if we bought a replacement boiler (new) and swapped out the kingfisher, if/when we extend, we'd have to buy another NEW boiler - we couldn't simply move the first new one. Plumber yesterday tells me this is cobblers?

B) Is the quoted cost for powerflush reasonable? interweb research seems to show it being a bit on the costly side, but I just don't know.

C) If the answer to (A) is that it IS re-locatable, then we think we're probably going to replace now, given the possessedness of the existing system coupled with enormous gas bills. With possibility of extension in mind - any recommendations as to what to go for boiler wise? I do understand if we replace the boiler we'd have to flush system anyway....but as noted earlier, I think it needs it regardless.

D) If we replace boiler - ANY ideas on what I'd need to budget? I did find one plumber near me that has a "boiler replacement calculator" on his website - this indicated around £1600 for a Worcester Bosch with Honeywell controllers and basic flush. Being suspicious, that seems low to me and sounds like we're going to get a whole load of "tssssssssssk, well you didn't mention it was in a house,...that's another £5k please"

Many thanks all
 
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What we currently have is a Potterton Kingfisher 2 - 23.5 Kw. Around 20+ years old.
A good boiler. You won't find many modern boilers which will last that long!

This is split into three "zones" controlled by Honeywell CM61NG wireless controllers.
Current regulations require two zones if the floor area is over 150m², so three zones may not be overkill if you have a large house and some rooms are rarely used. How many receiver boxes do you have for the CM61NG's - three or four? You should have four - one for each motorized valve on the three zones and one for the boiler.

To add fuel to the fire, the controllers are mad. They don't seem to do what you want at all....the heating comes on when it wants, it won't come on if you want it to and some radiators will heat up when others (in the same zone!) won't.
Did the previous occupants leave the instructions for the controls? They have a feature called "optimization", which automatically adjusts the turn on time according to the weather.

Rads not heating up could be due to poor balancing. Turn off the ones which do heat up and see if the reluctant ones spring to life. If they do, it's a balancing problem.

However, last week, whilst running a bath for my year old daughter, the hot water failed. At the same time, the central heating has failed for all three zones - although there is SOME heat going to one of the zones. We had a plumber round yesterday who didn't really seem confident of the answer, but suggested a powerflush.
Did he get the system working again? If so, what was the problem?

We had been told previously you are not allowed to re-locate a boiler now. I.e. if we bought a replacement boiler (new) and swapped out the kingfisher, if/when we extend, we'd have to buy another NEW boiler - we couldn't simply move the first new one. Plumber yesterday tells me this is cobblers?
Yesterday's plumber is correct. You will probably have to purchase a new flue, but that's a relatively minor cost.

Is the quoted cost for powerflush reasonable? interweb research seems to show it being a bit on the costly side, but I just don't know.
British Gas charge up to £700 for a powerflush - but they do give a "lifetime" guarantee.

With possibility of extension in mind - any recommendations as to what to go for boiler wise? I do understand if we replace the boiler we'd have to flush system anyway.
That's the "piece of string" question!

How big will the extension be?
How many bathrooms/showers do you have?

It might be worthwhile calculating your current requirements, using the Boiler Size Calculator, to make sure your existing boiler is up to the job. Also check that you have enough radiator capacity using the data in the
Stelrad Elite Catalogue.

If we replace boiler - ANY ideas on what I'd need to budget?
NO! Decide exactly what you want to do, then ask three reputable (i.e recommended by people you can trust) installers to give you a quotation.
 
Thanks so much, that's a very useful reply. To answer some of the questions raised:
previous owner has not left any information on the system, other than the parting statement "it's very simple" (ha!) - from what you've said it does sound remarkably like an optimisation programme is in effect. Any clue on how to tell if there is an optimisation programme in effect, or stop it?


Current regulations require two zones if the floor area is over 150m², so three zones may not be overkill if you have a large house and some rooms are rarely used. How many receiver boxes do you have for the CM61NG's - three or four? You should have four - one for each motorized valve on the three zones and one for the boiler.
House size is about 180 sq m and I'm quite happy that three zones is sensible (for example it was split into three as the previous owner sublet one chunk of the house). There are indeed four control units in the boiler house. Yesterdays plumber confirmed all of these are still functional.

Did he get the system working again? If so, what was the problem?
Nope - said the powerflush was the first step, before taking system to pieces...I have tentatively booked them in to do this a week today - earliest they could do - but I am now wondering if just biting bullet and replacing boiler is best bet.

Agree on point of balancing - but certainly I'm of the (very, very inexpert!) opinion that a flush would be a good starting point.

If we do extend, the intention is to create a fourth bedroom and possibly an additional bathroom. In all likelihood, for what we have in mind, the addition would be one room and possible addition of a couple of rads - not wholesale, multiple room changes. To add colour to this, the house is an old gamekeepers cottage, so we have the main living space which is two storey - we wouldn't touch this - and then a single storey annex which was used for breeding the birds originally (but subsequently done up for subletting). Therefore, whilst not quite true, the extension would turn the single storey into double storey for the extra bedroom but that's it.

I'll have a play with the calculators you kindly linked and see what that throws up, but I think right now my gut is saying chop the boiler out now.
 
Any clue on how to tell if there is an optimisation programme in effect, or stop it?
Why stop it? It takes a bit of getting used to, but it's very effective. When optimization is enabled you just set the time at which you want the house to be up to temperature and the controller does the rest. So, if you get up at 7am and want the house up to 20C by then you just set those parameters for the first setting of the day. There's no longer any need to think "It's going to be colder tomorrow, so I had better bring the heating on half an hour earlier". The controller does this automatically.

Here's how you check if it is turned on:

Press OFF
Press and hold INFO (I) button and press PROG 3,4 together
Press Clock + or - until screen reads: 15:Op and either 1 or 0.

If it has a 1, it means Optimization is ON.

You can change this to OFF (0) by pressing the Temperature up or down buttons. (The display will flash)

Press the Info button to confirm.

Press Auto, Man of Off button to exit set-up mode.

Nope - said the powerflush was the first step, before taking system to pieces...I have tentatively booked them in to do this a week today - earliest they could do - but I am now wondering if just biting bullet and replacing boiler is best bet.
You would need the system to be cleaned when a new boiler is installed, otherwise the boiler manufacturer will not accept responsibility under the warranty. However, I think the installer should have done some more investigation to make sure there was nothing electrical/mechanical stopping the boiler from working.

Agree on point of balancing - but certainly I'm of the (very, very inexpert!) opinion that a flush would be a good starting point.
Agree that trying to balance a badly sludged system would be very difficult.

To add colour to this, the house is an old gamekeepers cottage
Named Mellors by any chance? :LOL:

the main living space which is two storey - we wouldn't touch this - and then a single storey annex which was used for breeding the birds originally (but subsequently done up for subletting). Therefore, whilst not quite true, the extension would turn the single storey into double storey for the extra bedroom but that's it.

I'll have a play with the calculators you kindly linked and see what that throws up, but I think right now my gut is saying chop the boiler out now.
Then you can use the boiler size calculator for the existing house and then for the modified house. You should divide the house into two parts - two storey and one/two storey.
 
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Do not see anything wrong with the setup.

I would give the £400.00 powerflush for cash a wide bearth. Get someone whose work is good and is reliable (talk to friends and relatives- avoid fancy adverts) to look at the system.
 
There are indeed four control units in the boiler house.
If the boiler house is an outbuilding, it should have a frost 'stat. In cold weather, the boiler can run continuously to protect itself from freezing. I wonder if that might be part of the problem. My frost 'stat was set to 5°C but actually turned on at 10°C. It might be worth checking yours, if you have one.

If they have cold spots on their radiators, is that too far gone for a chemical flush?
 
If the boiler house is an outbuilding, it should have a frost 'stat. In cold weather, the boiler can run continuously to protect itself from freezing. I wonder if that might be part of the problem. My frost 'stat was set to 5°C but actually turned on at 10°C. It might be worth checking yours, if you have one.
Well spotted. ;)

You actually need two thermostats. The frost stat closes if the temperature drops below, say, 5°C. The pipe stat, in series with the frost stat, opens when the water temperature reaches about 10°C. This prevents the boiler running continuously.
 
never come across a zoned system shutting down totally because it needs a "powerflush"
Get an honest recommended guy round, might still cost lots of money. The proverbial powerflush is not the answer to every heating problem, unfoutunatly the unscrupulous or inexperianced think it is the miracle elixer.
 

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