I am going to replace the entire radiator system in my house, including all the pipes. The system will be driven by a combi boiler and the mains water pressure is 4 bar.
Will 15 mm pipe be OK for the entire radiator circuit?
Thanks
Mr F.
Probably not.
Mains pressure is utterly irrelevant. What's important is how fast the pump can drive the flow round the circuit, through the radiators, and back. It's got to be fast enough that the boiler can output its full output, without exceeding its maximum output temperature. (and indeed, with a combi, you want it quite a lot lower for efficiency.)
Unless you have a very small house, with all the radiators next to each other, it's likely that you will need to use 22mm, at least for the flow/return.
Think you need to do a little research before starting this project.
See my reply to your previous question. Take a sketch of your house, and your pipe runs into the Harrision McCarthy shop and they will work all this stuff out with you.
If you are unlucky enough to live miles from Manchester, then a local plumbers merchant may do the same trick for you.
Rick
True.
Not quite.The pipe sizes have to carry the required amount of heat.
See above.
Uh!
He needs to calculate the heat load and pipe sizes. He has a system. If it works replace the pipes type of type, if he can't do the calcs, and over size in some instances.
Probably not. 15mm pipework will have a power limit of around 6kW unless the flow rate is high enough to be noisy.
And take no notice of this one too. He was encouraging people not to service gas boilers. He didn't service his for 18 years. Yes you heard it right.
So you think 15mm will be ok for the entire installation?
Remind us again of your qualifications?
Chief wanker and what else?
You could get a nearly ideal CH system, with 6mm ID copper tube, Taking a flow rate of 1m/s, 1/40l of water per second, so 100W/K, so at
40K delta-t, that's 4Kw. Call it a needed flow rate for 20Kw of 5m/s. You will need to drastically upgrade the pump, but it's not even getting close to levels where it may damage the pipe.However, this will rarely, if ever make sense, unless the structure is concrete, with a high diamond content, and meter thick walls.
It turned out that when I went into the kitchen, for a cocoa, I found a length of 6mm ID hose, 2m long. At 1m head, it flows 250ml in 20 seconds, or 12.5ml/s. Or 1/10th the flow needed to get to 5m/s. Say 10m head/m, for a 30m run, and you get to 30bar pressure. Conventional radiators may have problems.
Oh my God not another one. It is bad enough having the Hibernian lunatic here. What tripe is he on about?.....
A super high pressure, high flow rate pump could do a heating system with
4mm pipes, but would make one hell of a racket. The pumps speed on a domestic system is limited by the noise and vibration it creates. That is why larger pipe sizes and slower pump speeds are required.I saw an experiments system once, using very small bore microbore pipes. Only spayed manifolds and "Y" tees used, with no elbows whatsoever anywhere, a tubed cooper boiler and clips with rubber anti-vibration inserts. A high speed pump was used. It worked. It only took the slightest deviation from the above a excessive noise was created. It was never taken up as it was deemed impractical. The time saved threading microbore would be offset by time intensive attention to other matters. Dropped and never seen again.
It may damage your ears and sleep though.
Lunacy reign firm in his mind.
It depends on the power capacity of your radiators and the system designed flow/return temperature difference. However, for most systems 6kW of rads is a good ballpark for 15mm pipe. 6kW is appromixately a one bed flat or one floor of a terraced house.
If you go below the recommended, you get a noisy system, but it still works unless it is drastically undersized. Designing for a modern 70/50 flow (which results in larger radiators) allows more power through the pipes than the old 82/70 design, so you could get away with up to 10kW, if you're feeling tight and balance the system right.
Generally speaking, however, it is best to run either a 22mm trunk with 15mm (or less) spurs to radiators, or to use a manifold system, with 22mm to the boiler and 15mm (or less) from the manifold to the rads.
Christian.
Using a condensing boiler, with a wide flow/return delta T, 20C plus, the pipe sizes can be smaller as more heat is transferred. The problem is pump noise. I doubt if 15mm would do on any domestic CH system, unless a very small studio apartment, which is little more than one room.
So our resident lunatic, who theorises about everything, but knows the practicallities of nothing, is at it again.
This is a DIY group. Buy all means theorise, but make sure everyone knows that's what you're doing. Unless you're about to recommend this super high pressure system that makes Concord sound quiet.
If not, shut the f*ck up.
The OP said house. Can't you read?
Which means hands on.
You were not involved then?
Still another hour and a half at that counter drivel, sell more tanks and make me some more money.
Hacksaw please. No plastic pipe today.
Or in your case hacksaw on.
However, if you wish to give details of your super high pressure central heating system using microbore throughout, please give details of where to purchase it so we can all have a good laugh.
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