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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Plumbing Questions >> installing central heating https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1110212496 Message started by JohnD on Mar 7^th, 2005, 4:21pm

Title: installing central heating
Post by JohnD on Mar 7^th, 2005, 4:21pm

I have agreed with a plumber friend that he will put in a combi boiler for me if I get all the pipework ready for him. I have done cold water plumbing before and plastic, but never central heating. He will do all the gas side.

I have got the bathroom plumbing ready and am now thinking about the central heating.

His instructions were 'Just' (I liked the 'just'!) raise a floorboard, run the pipes up the centre of the living room, tee off to the hall, do the same in the bedrooms and bob's your uncle! Simple!'

Yeah, right. Like rocket science! I have been looking in plumbing books - Collins etc - but they are all quite useful if you want to maintain something but useless on c.h. design and installation.

A few questions.

1. Is there any particular depth under floorbaords which pipes should be laid? Or is a 3/4" notch still o.k.?

2. End feed or solder ring fittings or doesn't it matter?

3. Where I tee off under floorboards and one pipe has to pass over another, is it best to have the bend in the flow side or the return side? Or doesn't it matter?

4. Years ago they used to use old carpet around pipe where they passed over joists to stop banging. What do I use now? Lagging?

5. When running my pipes up the centre of the room to a radiator at the far end of it, I assume that, as the joists are parallel to the wall I am running to, I run the pipe right over the first joist virtually up to the wall (there is a 2" gap between the joist and the wall) then fit a right angle bend to each pipe and after 2' 6" on each pipe then come up through the floorboards to the rad. This will mean that there should be enough give in the pipe to get the rad off.

The reason I ask is that it would be simpler to put my bends in one joist further back, and then run two pipes straight to the rad some 5' apart, but then I assume I would have more difficulty lifting the rad off the brackets for decorating etc. unless there was a very deep cut in the joist indeed, which wouldn't be good practice. Have I got it right?

6. Finally, should I lag the hot pipes and c.h., pipe under the floorboards? I assume this would prevent floorboard shrinkage and heat wastage but have never seen it mentioned.

Thanks

JohnD

Title: Re: installing central heating
Post by billythekid on Mar 7^th, 2005, 9:46pm

wrote on Mar 7^th, 2005, 4:21pm:

1. Is there any particular depth under floorbaords which pipes should be laid? Or is a 3/4" notch still o.k.?

2. End feed or solder ring fittings or doesn't it matter?

3. Where I tee off under floorboards and one pipe has to pass over another, is it best to have the bend in the flow side or the return side? Or doesn't it matter?

4. Years ago they used to use old carpet around pipe where they passed over joists to stop banging. What do I use now? Lagging?

5. When running my pipes up the centre of the room to a radiator at the far end of it, I assume that, as the joists are parallel to the wall I am running to, I run the pipe right over the first joist virtually up to the wall (there is a 2" gap between the joist and the wall) then fit a right angle bend to each pipe and after 2' 6" on each pipe then come up through the floorboards to the rad. This will mean that there should be enough give in the pipe to get the rad off.

The reason I ask is that it would be simpler to put my bends in one joist further back, and then run two pipes straight to the rad some 5' apart, but then I assume I would have more difficulty lifting the rad off the brackets for decorating etc. unless there was a very deep cut in the joist indeed, which wouldn't be good practice. Have I got it right?

6. Finally, should I lag the hot pipes and c.h., pipe under the floorboards? I assume this would prevent floorboard shrinkage and heat wastage but have never seen it mentioned.

Thanks

JohnD

Some answers.

1: ¾ notch will be fine. (mark the boards so you dont nail the pipes)

2: Doesnt matter, if you are confident enough use end feed as they are cheaper, if you havent done too much soldering stick to the solder ring fittings. If using solder ring dont be tempted to add solder, just heat until you get the nice silver ring round the fitting. TIP: use plenty flux and wipe off with damp cloth once joint is made for a clean finish.

3: Doesnt matter, but give yourself plenty room so you dont need a tight bend, less bends the better.

4: Lag all your pipes anyway. lagging will do fine for creaking and dont cut your notches too tight.

5: Leaving plenty slack from the last joist might give more play, however to get the rad off the play is better horizontally i.e play in pipe side on to rad. I would cut the joist an inch or so for this notch laterally so this play is there(remember the floorboard will need an inch "hole" too.)

6: See 4

Hope this helps.

btk

Title: Re: installing central heating
Post by JohnD on Mar 7^th, 2005, 11:44pm

Thanks, BTK - very helpful!

As to lagging, any particular type? Polyethylene o.k., or should I go for the old fashioned hessian stuff?

As to giving myself plenty of room, should I raise two adjacent floorboards and put a pipe under each - or just put one either side of the same floorboard?

Oh yes, knew there was something else - how long can a straight run of CH or hot water pipe be be before I have to put an 'omega loop' in to allow for expansion?

Thanks again

JohnD

Title: Re: installing central heating
Post by billythekid on Mar 8^th, 2005, 9:25am

wrote on Mar 7^th, 2005, 11:44pm:

Dude its 2005, never let me hear the words hessian lagging again. TIP,: Lag the pipes before you install them. then you only have small sections at the joints to lag once its in place.

2 boards, you'll need the room to work at them anyway.

not long enough in a domestic pumped heating system.

you are over complicating things now lol.

2 runs, flow and return down middle of house teeing off to rads. just like yer m8 said! lol.

btk

Title: Re: installing central heating
Post by CWatters on Mar 8^th, 2005, 2:58pm

I'm not a plumber but...

Wouldn't any plumbers recommend plastic pipe for this job?

I mean you can drill rather than notch joists.

No soldering.

No pipe bending.

Less knocking.

Any disadvantages?

Title: Re: installing central heating
Post by JohnD on Mar 8^th, 2005, 4:42pm

Plastic pipe? Not on your nellie! Quick, convenient and totally unproven in terms of its long term suitability.

Speaking only as a talented amateur I'll carry on soldering.........

JohnD

Title: Re: installing central heating
Post by supersparky on Mar 8^th, 2005, 4:45pm

unreliable, ive always seen it sag under the floor.

recomended by me if you want a flood.

not a plumber but ive asked a few plumbers this and ive only seen one use it for a full system....and he has had to go back about 6 times.

it was installed in 2002 lol

ss

Title: Re: installing central heating
Post by CWatters on Mar 8^th, 2005, 7:06pm

Here in Belgium it seems to be much more common than in the UK. The impression I get is that in the UK few people have sufficient experience with the stuff to get it working right. I hear once you are aware of it's quirks it's a lot quicker to install.

If I've done my sums right there will be about a kilometer of the stuff concreted into the UFH system of my house - so it better not leak!

Title: Re: installing central heating
Post by supersparky on Mar 8^th, 2005, 7:25pm

plastic plumbing like that has been arround for about 15-20 years i beleve,,,....hardly new ;)

over here its seen as diyer standard

ss

Title: Re: installing central heating
Post by billythekid on Mar 9^th, 2005, 10:35am

plastic pipe can be very good when properly installed. Personally I only use the stuff for very hard to get to stuff, some showers etc. I always use copper and end feed(where possible) i feel that the main advantage with copper is that it doesnt tend to sag and gives a far higher finished look than plastic. I'd never recommend a DIYer to use it as the joints need to be well made and away from things like joists etc where they might get knocked off, remember most plastic joints are push fit and are removed by simply pressing a ring towards the joint, if these are against anything they can pull themselves off(much like a sparkie, lol).

I would only use plastic where it will never be seen, which granted a heating system pipework is never seen. But just not worth it IMO. I would stick to copper specially since its your own house, you might never see it, but you'll always know whats there! Peace of mind! lol

btk

Title: Re: installing central heating
Post by greg on Mar 9^th, 2005, 7:21pm

I will always use copper where and when i can - especially if its on view - some sites tho now specify plastic pipe so they can have the intermediary floors down before plumbers / sparks do their first fix. Plastic plumbing is fine when its installed properly - which it usually isnt - needs to be clipped every 500mm - needs to be cut with proper pipe cutters, not a hacksaw or stanley knife - as BTK says joints need to be installed properly so they are not under too much strain. Ive installed loads of Hep2O with no major problems but have been out to many leaks on the stuff put in by DIY'ers / builders because they dont really understand what they are doing - sparks on sites dont like it coz its a nightmare to bond when youve got plastic under floors and copper coming up thru floor to rads / sanitaryware

Title: Re: installing central heating
Post by PEDANTICVINDICTIVEMAN on Mar 9^th, 2005, 9:10pm

Done loads of complete CH systems in Hep20 barrier pipe, wouldn't use anything else now, had no problems, done complete bathrooms and kitchens with no problems either, no way can you pul off a Hep20 fitting either slimline or the demountable fittings if they are fitted correctly, I dont trust the white speedfit type of stuff though as it doesn't seem as robust, I mix and match copper and Hep20 together with no problems at all.

Title: Re: installing central heating
Post by bstyle on Mar 9^th, 2005, 10:47pm

Agreed, Hep has got to be the best on the market but most expensive.

Title: Re: installing central heating
Post by billythekid on Mar 9^th, 2005, 10:57pm

Yeah i've never had any problems with the stuff either, well if you dont count 'it looks like shït' as a problem. Loads of clips, formed bends. offset anyone?? Gimme a good copper install anyday of the week.

btk

Title: Re: installing central heating
Post by bstyle on Mar 9^th, 2005, 11:14pm

I normally would have it hidden under the floor.

Title: Re: installing central heating
Post by thescruff on Mar 12^th, 2005, 9:47am

Who gives a toss what they look like under the floor, wELL I DO FOR STARTERS

Plastic rubbish.

scruff ;D ;D

http://img.photobucket.com/albums/v395/thescruff/Imgp0921-m.jpg

And try this in plastic

http://img.photobucket.com/albums/v395/thescruff/Imgp0990.jpg

Title: Re: installing central heating
Post by greg on Mar 12^th, 2005, 4:28pm

Scruff, careful when you fill up m8 - seem to have a couple of open ends in that second picture ;)

Title: Re: installing central heating
Post by thescruff on Mar 12^th, 2005, 5:01pm

wrote on Mar 12^th, 2005, 4:28pm:

Scruff, careful when you fill up m8 - seem to have a couple of open ends in that second picture ;)

Work is still in progress.

Title: Re: installing central heating
Post by greg on Mar 12^th, 2005, 5:16pm

Is it a local job for you or are you still in London

Title: Re: installing central heating
Post by thescruff on Mar 12^th, 2005, 5:54pm

London still ;D ;D ;D m8

Title: Re: installing central heating
Post by greg on Mar 12^th, 2005, 6:19pm

Nearly a year now isn't it since you been up the smoke

Title: Re: installing central heating
Post by JerryD on Mar 12^th, 2005, 6:29pm

flippin' heck!

Putting that floor back down is NOT a job for the apprentice :o :o ::) ;D

Title: Re: installing central heating
Post by thescruff on Mar 12^th, 2005, 6:36pm

piece a cake, two pipes under each board

::) ::)

Title: Re: installing central heating
Post by CWatters on Mar 12^th, 2005, 7:00pm

Is that pipe marked "gas" legal?

Title: Re: installing central heating
Post by greg on Mar 12^th, 2005, 7:20pm

Why would it not be legal?

Title: Re: installing central heating
Post by thescruff on Mar 12^th, 2005, 7:23pm

wrote on Mar 12^th, 2005, 7:00pm:

Is that pipe marked "gas" legal?

It complies with Essential Gas safety if thats what you mean, Pipe is protected in the notch with "Armaflex" self adhesive lagging tape as is the other pipes.

Title: Re: installing central heating
Post by CWatters on Mar 12^th, 2005, 7:58pm

I thought gas had to be run in thicker pipe, usually steel, and painted yellow, but I'm no trained pumber.

Title: Re: installing central heating
Post by supersparky on Mar 12^th, 2005, 8:21pm

cooor the sparks would love that!

watch the plumbers who only do domestic struggling with the stocks and dies and bending machines...hahahhaha ;D

ss

Title: Re: installing central heating
Post by thescruff on Mar 12^th, 2005, 8:38pm

wrote on Mar 12^th, 2005, 7:58pm:

I thought gas had to be run in thicker pipe, usually steel, and painted yellow, but I'm no trained pumber.

Copper is ok if protected from nails etc which it will be, marker tape is ok and not shown in pic.

The compression fitting is not allowed and only being used to temporary cap the pipe end subject to being extended after other work which took priority.

Title: Re: installing central heating
Post by billythekid on Mar 12^th, 2005, 8:55pm

wrote on Mar 12^th, 2005, 8:21pm:

cooor the sparks would love that!

watch the plumbers who only do domestic struggling with the stocks and dies and bending machines...hahahhaha ;D

ss

Shakes head....

I only do domestic, but i'd challenge any spark to any pipebending in MI/mild steel. I'll even use a hand bender and let y'all use ther hydraulic machine, and hand cut the threads and let you guys use the electric die.

btk

Title: Re: installing central heating
Post by thescruff on Mar 12^th, 2005, 8:58pm

It is a Domestic installation BTK

all 28mm with a 35/42mm gas supply

Title: Re: installing central heating
Post by greg on Mar 12^th, 2005, 10:08pm

Here SS is starting in on us poor plumbers ;D

I have no problem bending steel pipe either hydraulic or heat bending - still have my stock and dies - must admit they've not seen daylight for a while ;)

It is not a requirement (but is good practice) to id domestic gas pipe

Title: Re: installing central heating
Post by supersparky on Mar 12^th, 2005, 10:20pm

HYDROLLICC CCC CCC and heeeeeaaat bending?

wassat... ???

lol, us poor old sparkies, you think we have big muscles cos were a bunch of wankas, the trough is we work hard without these gadgets and heat methods....coooorrr what are you lot like :-*

lol

ss

Title: Re: installing central heating
Post by billythekid on Mar 12^th, 2005, 10:47pm

wrote on Mar 12^th, 2005, 8:58pm:

It is a Domestic installation BTK

all 28mm with a 35/42mm gas supply

LMAO, ummmmm, perhaps i should have been more specific eh? lol

btk

Title: Re: installing central heating
Post by supersparky on Mar 12^th, 2005, 11:21pm

wrote on Mar 12^th, 2005, 8:55pm:

btk you would challenge em to what exactly :-*

you would get caned if it was a race!

we have to bend mild, stainless, galvanized ect and by hand :D and thread it

dont need electric or hydrolic cccic cccccc

ss

Title: Re: installing central heating
Post by thescruff on Mar 13^th, 2005, 1:07am

4" conduits ;D ;D

must be big cables lol

Title: Re: installing central heating
Post by supersparky on Mar 13^th, 2005, 1:16am

4 inch lol, not talkin about stuff that big!

2 inch max

and MI to me means mineral insulated;)

ss

Title: Re: installing central heating
Post by greg on Mar 13^th, 2005, 5:37pm

must be a fair sized house scruff if your running 28mm everywhere?

Title: Re: installing central heating
Post by PEDANTICVINDICTIVEMAN on Mar 24^th, 2005, 7:11am

Who gives a toss what pipes look like under the floor, I use copper where exposed for a neat finish where it does matter, I dont care if plastic droops under floors or looks crap, as long as I get finished it works doesn't leak and I get my money.

Title: Re: installing central heating
Post by billythekid on Mar 24^th, 2005, 12:44pm

yeah thats what i thought.

Title: Re: installing central heating
Post by Stoday on Mar 30^th, 2005, 1:39am

wrote on Mar 7^th, 2005, 11:44pm:

Oh yes, knew there was something else - how long can a straight run of CH or hot water pipe be be before I have to put an 'omega loop' in to allow for expansion?

The length of copper pipe will expand by 1mm per meter for a 55 deg C temperature change. That will cause the pipe to creak over joists unless you lag or stick a bit of felt under the pipe.

In a long run you don't need an omega expansion configuration, but you do need to allow the bends/elbows to take up the expansion. E.G. if you have a 5m run, allow for 5mm expansion.