Central Heating System replacement advice

[Random-Paddy]

Hi all,
I've read forum posts on DIYnot for a good few years now, searching usually finds the answers I've wanted so far but I'm after a bit of advice on how to proceed with a bigger job now really. I know there will be some opinions based on my diy approach but I'm happy to listen to all to get some advice.

I've got a 4 bedroom house (1980's) that has been plumbed in mostly 8mm microbore acorn piping for the central heating. There's an Ideal Elan boiler in the kitchen which I believe was installed when the house was new. I took over the house just over a year or so ago. Whilst we haven't any major issues with the heating so far, the boiler has served its time we think and we are keen to replace it, the hot water cylinder and the open vented central heating system for a combi boiler and pressurised system.

I've had a couple of plumbers come to quote on replacing the whole lot and gotten quotes back. Now whilst I've no major issue paying somebody to replace the boiler and pay for a decent boiler, I'm a little hesitant to pay somebody to replace the pipework and at the prices quoted. Before anyone suggests I'm being tight, I know this and I appreciate it but I'm also fairly logical and pretty good with diy (yes it doesnt make me an expert). I do have other reasons for trying to do this as economically as possible but I'll not get into that on here. I'm planning to be in the house for at least another 10-20 years so knowing what is where and how it went in is important to me, but having a sound setup is also important. In my previous experience, getting a trade person in doesn't always deliver that.

Anyway, to explain, the Boiler is located in the kitchen. The boiler output goes upwards from the top of the boiler into the ceiling of the kitchen. It runs between the ceiling of the kitchen and the tiled floor of the bathroom to the landing in a flow and return 22mm or 3/4" pipes. From here there are manifolds going out to the 8mm microbore acorn piping in the hall landing upstairs. These pipes feed and return from the 8 radiators in the house. I've had the floor up and taken pictures and its quite clear where the pipes go from there.

Now, after speaking to a few plumbers, because the existing pipework goes downstairs between the plasterboard and brick work and a few other places, trying to repipe in copper would either mean a huge amount of ripping and costs or its not really possible. Another plumber had suggested MLCP but again, between pre-forming bends before it goes in, its not ideal either, so I'm pretty resound to having to use plastic.

Based on having to use plastic and having already figured out that all the runs can be done in 15mm plastic pipe direct to the radiators, I started to wonder how difficult this would be. In simple, non-professional mind, the hardest will be running the plastic pipes behind the plasterboard and through the joists etc. Actually connecting to the radiators already in place, I do not think will be a major feat of plumbing, yes it'll require new valves on each radiator, but as I'm planning to get TRV's for all radiators, this needs to be done anyway. The plumbers I spoke to preferred to have plasterboard open more to have easier access and reduce my costs, but add to the additional work I'd have after to patch up. My logic being, if its my own time, I can spend an extra hour fishing pipe through a wall to save £50 and drag my son into it for experience.

My questions are, from the experienced plumbers and diyers out there, would you advise against taking on this kind of work. My thoughts were to re-plumb the central heating back to the flow and return pipes from the existing boiler (the ones in the hall landing, not next to the boiler!), then get a plumber in post this work, to fit the new boiler. I realise they will not guarantee the pipework, just like they wouldn't if I were just getting a new boiler without fitting the piping but can anyone suggest any major downfalls I should be aware of? Possibly the difference in pipe size and the existing pump spring to mind, but would this just mean slower to heat radiators until the new boiler is fitted or new pump.

Does anyone have any thoughts or comments? Also as I would be dropping plastic piping down behind the plasterboard to the radiators, I was trying to avoid the issue of the plastic pipes kinking with the setup show in this photo

Pipe comes down the wall in the centre of the rad, comes out of the wall in the middle of the rad through a radiator outlet plate and gradually curves to the 90degree compression fitting attached to the TRV. The other end of the plastic piping would be directly attached to a manifold with again a compression fitting. I've worked a little with compression fittings before and outdoor water pipes so think I'm best to use them here. I think its the simplest solution with only the 90degree fitting being the extra joint and potential flow restriction.

Before my post goes rambling on, anyone any thoughts or questions?

Thanks

Paddy

 

[Agile]

Most would say replace it in 15 mm even if you must use plastic pipe.

You don't exactly say it but you may mean could you take both pipes from each rad back to a central manifold. That would work too.

 

[Random-Paddy]

Current setup is two seperate manifolds (well currently a single and 6 way manifold in series connected to feed and another of the same connected to return. Plan is to replace them with two sets of 4 or more manifolds in series in the same setup. I'm not really looking to change the design/layout, just replace the piping with 15mm and new manifolds, new trvs.

Here's an image of the current setup.
http://www.random-inc.co.uk/download/ch.jpg

 

[Razor900]

I'd fit an Intergas and run it open vented. There would be no more chance of leakage than there is with your old boiler because the pressure would be the same as it is now.

 

[muggles]

I'd fit an Intergas and run it open vented. There would be no more chance of leakage than there is with your old boiler because the pressure would be the same as it is now.

What he said. Get an Intergas ECO RF then you can have a combi fitted to an open vented system, and for an added bonus you'll have a really well designed, well built, reliable boiler with a 10 year warranty

 

[Random-Paddy]

Hi Guys,
thanks for the info, I wasn't aware of the intergas boilers that fit to an open vented system, I'll put that down to the plumbers not advising on it. Still due to the stories we've heard about the acorn piping and also the way some of it is fitted (kinked in some sections) and the fact we will be getting a new boiler, we are fairly committed to getting the pipework done at this time also. The boiler is the something we need in, we feel and we'd rather not tempt fate with a new boiler and the existing piping based on the advice from the plumbers that have been out.

I was hoping for some comments on approaching the re-pipe from a DIY perspective. Do you think its a suitable DIY task or something better left to a plumber? Thanks to Muggles, Razor900 and Agile for the comments so far.

 

[bernardgreen]

re-pipe from a DIY perspective. Do you think its a suitable DIY task

If you can solder pipe work and do it in summer when you can cope without heating for a few days ( weeks ) then it can be a DIY task.

 

[Random-Paddy]

I'm not planning on using copper or changing anything at the boiler end so wont need to solder from my understanding. All compression fittings onto plastic piping. I've already had sign off from my wife to take the heating out for a few days. Planned to just loop the 22mm feed and return from the boiler so that the boiler can still heat water and not cause an issues in the off chance somebody turns on the heating. That way I can work on the radiators at my leisure. Alternatively, I'll blank off a few of the manifold ends to radiators at a time and do it bit by bit over a few weekends. Upstairs radiators not really needed during the late spring summer.

Anyone have any advice on which plastic pipe to use? I see Wickes have JG speedfit 15mm x 50M for about £60-70. I take it that's sufficient for the job?
Also anyone seen a female 90degree elbow compression fitting in chrome where the female end has the swivel nut? I've found the elbows that are fixed but I was concerned that when tightened it wont align with the trv's so I'd need a coupler in the middle. Similar to below but need the female end to tighten but not have to turn the elbow if that makes sense. Would prefer chrome to match the TRV bodies.
http://www.plumbcenter.co.uk/product/conex-403sf-female-iron-swivel-elbow-15mm-x-1-2/
Think this is what I'm after
http://www.plumbingproducts.ie/chro...chrome-327-compression-swivel-elbow-15mm.html


Thanks

Paddy

 

[Agile]

We don't know your house size but unlikely 50 m is going to be enough with a central manifold. Might even need three lengths.

Tony

 

[Random-Paddy]

Thanks, I had been thinking I'd need a 25m with the 50m but was just going to pick it up as I go along. Not a massive trek to Wickes and the runs aren't massive. The manifold is pretty central and the rads are on internal walls around and beneath the manifold really. Any thoughts on JG speedfit pipe for central heating with compression fittings? Any other branded pipe worth looking at?

 

[Razor900]

Before anyone whinges about disclosure:

I work for Intergas although I fitted the boilers for almost ten years first but if you check them out you'll find that not only can they run open vented you can actually tell them that they are a simple water heater so you could get a gas fitter in to install one and leave it running on hot water only with absolutely no central heating pipework installed.

Then when you're ready and it's all connected up it's pressing a couple of buttons and you're all good to go - the fitter will have already done the top secret gas stuff so it's fine for you to do the rest yourself although for peace of mind I'd recommend you get them to pop in for the big switch on

 

[muggles]

Thanks, I had been thinking I'd need a 25m with the 50m but was just going to pick it up as I go along. Not a massive trek to Wickes and the runs aren't massive. The manifold is pretty central and the rads are on internal walls around and beneath the manifold really. Any thoughts on JG speedfit pipe for central heating with compression fittings? Any other branded pipe worth looking at?

Speedfit will be fine (you'll almost certainly not be pressure testing to the required pressure for the warranty so it makes little difference what you use), use the layflat stuff to avoid getting too tangled up in the coils, and male sure you use the inserts without the o-rings on compression fittings. Personally I don't like compression on plastic, but then I generally avoid using either wherever possible. You'll use it up a lot faster than you realise!

 

[vulcancontinental]

Good to see some whinging has instilled some candour into your posts Razor.

For a bit more from me I'd swap the boiler for a nice little Vokera Mynute VHE open vented boiler and even though you don't care for the idea I'd replace all the pipework with copper. Generous with pipe sizes, no more than 3KW through 15mm the rest in 22mm. If you don't have a 22mm cold feed from the expansion cistern in the loft and you probalbly will not replace that with 22mm. Clean the system including the F&E, set the pump on speed one, look after the boiler with a proper service and you'll get a good 15 to 20 years from it.

Not fashionable to say this sort of thing.

I've been doing this for three times the length of time razor has been fittiing those boilers and I know it works and have systems out there with original non-cast iron boilers for that length of time to prove it. Then again I might know nothing.

I do work for Vokera but that's a lovely little boiler, the only drawback being it does need a pump overrun but I think the Elan needed one too so the wiring will be there.

 

[Agile]

Before anyone whinges about disclosure:

I work for Intergas although I fitted the boilers for almost ten years first

Well you had better post up your tax returns before Jeremy asks for it.

 

[PullerGas]

It's 10mm non barrier Acorn you have there matey. The Acorn will be breaking down & the system will be full of 'Tea Leaves'. The problem is air ingress through the wall of the tube.

It looks like a re-pipe is required, if you're lucky you may be able to retain your radiators if they're flushed.

Intergas is one of the best boilers on the market, but like all boilers your system needs to be as clean as Nun's knickers.
HTH