Help! Is partial replacement of my old GCH system possible?

[mike2004]

Dear All,
I'd greatly appreciate advice about the following:

We've recently moved into a 1960s house, with an old GCH system with an old Potterton Kingfisher (over 30 years old) boiler and skirting rads in all rooms. The DHW (gravity system) and GCH feed pipes at the boiler are all 1.5 inch iron. The pipes feeding the rads are mainly 1 inch iron, although those feeding the bathroom rads are 1 inch copper. Its a 5 bed house, with about 13 rads in total.

There are a number of problems were getting with this system.

Firstly the gas consumption seems very high. From weekly meter readings its about 160KWh per day (or about £7 a day).

Secondly, when the heating is on, there's an almost continual clicking from the rads and the pipes (a real problem at night!). I think this is because of the design of the skirting rads, with lots of little metal fins around the main pipe) - see this pic:

Untitled

• mike2004
• 2 Nov 2008
• 1

The third problem is that the house never seems to get very warm. Admittedly we're not having the system on full blast - mainly because of reasons (1) and (2) above, but even so, the house feels really cold.

I'm therefore trying to get some quotes for replacing (or partially replacing) the system. In addition to general advice about these problems, there are 2 questions I'm wondering about:

1) Is it a problem to have a mixture of iron and copper pipes in the same GCH system? (i.e. electrolytic reactions, corrosion, etc?)

2) Will it be best to get all the central heating pipework replaced to modern copper pipes at the same time as replacing and resiting the boiler (with a powerful Valliant heatstoring condensing one) - or will it be fine to keep the old pipework and maybe replace the noisiest 1 or 2 of the old rads?

Any advice about this all would be really helpful,
thanks
Mike

 

[ChrisR]

Anything is possible, copper and steel rads are mixed in most systems. But the ferrous stuff rusts. If you can afford it, strip the lot out, or it's likely to be harder later.

 

[mike2004]

If you can afford it, strip the lot out, or it's likely to be harder later.

Thanks for the reply. In addition to stripping out all the existing rads, are you suggesting its best to strip out the existing pipework too? One problem with our house is that the ground floor is hard, and has no cellar (concrete floors with parquet on top). So if we were going for a full pipework replacement, we'd need to drop pipes to the ground floor rads from the floorboard-space of the first floor.

thanks, Mike

 

[gas4you]

You can basically replace your heating system in whatever 'sections' you wish.

It will however be more cost effective to do it all in one go, rather than abit at a time, but then only you know your budget and what you can afford at any one time.

 

[muggles]

Best idea is to get a few plumbers in to give you some estimates

 

[mike2004]

You can basically replace your heating system in whatever 'sections' you wish.

It will however be more cost effective to do it all in one go, rather than abit at a time, but then only you know your budget and what you can afford at any one time.

You're right Dave that a big factor in my decisions here is the budget. What would you say would be a ball-park figure to be looking for in the quotes I get? As I said earlier, the house is 5 bed, 13 rads in all, and if we went for a Vaillant eco plus 937 boiler (and stripping of existing boiler, hot cylinder and cold storage tanks). We would keep the existing hot water system copper pipes, but replace the current heating system pipes with new copper and/or microbore to all rads. We're in Cambridge, if that affects the quotes(?).

Thanks,
Mike

 

[gas4you]

VERY approx ball park figure would be £5000- £6500 + VAT for a full new system, depending on what needed stripping out and what could be left to be used.

 

[mike2004]

VERY approx ball park figure would be £5000- £6500 + VAT for a full new system, depending on what needed stripping out and what could be left to be used.

Thanks Dave, and (sorry to pile on all these questions...) how about a very rough idea for doing the boiler replacement (with the Vaillant 937 as before), and replacing all 13 rads, but using all of the existing GCH pipes (these are a mixture of 1 inch iron and copper around the various rooms). i.e. simply replacing the boiler and the rads.
thanks,
Mike

 

[sambotc]

Hi,

All of the skirting board heating systems i have seen like pictured above are 1 pipe systems with a 22mm pipe in and out of each 'radiator'

This would explain your high running costs and low performance.

Most manufacturers will advise against fitting a new condensing boiler onto this system but allow it providing it works well (which i would guess it is not)

Sam

 

[gas4you]

As the majority of the cost would be borne by the supplying and fitting of the boiler and radiators, I would not envisage saving a great deal on the above very approx costing, possibly £500-£800 . I know your budget sounds quite tight, but I would really recommend not saving this small amount, but having the whole job done properly.

Can you save a bit off another budget somewhere?