Installing new plinth heater 10mm pipe

[Lucky245]

My house is fitted with 10mm pipe for whole heating system and I am putting in new kitchen so a plinth heater is the way to go. Chosen a smiths over myson as most people recommend it. Question is to join heater I need 15mm so how close should I be before upscaling pipe. The heater is bigger than required as I'm assuming on loss of heat flow due to change in pipe dimension.

 

[ShaunCorbs]

What size heater is it (kw)

Because normally there in 15mm for a reason

 

[Lucky245]

What size heater is it (kw)

Because normally there in 15mm for a reason

2.2kw at 75 degree or 1.7kw @ 65 degree

I could go for SS5 or SS7 to be adequate for room size but always found they exaggerate btu outputs

Picture shows SS3 up to SS9

 

[townfanjon]

When hou say your house is 10 mm pipe everywhere, I assume you have a manifold system , please be aware you will need a seperate flow and return to your heater , dont just tee off a nearby rad

 

[Lucky245]

When hou say your house is 10 mm pipe everywhere, I assume you have a manifold system , please be aware you will need a seperate flow and return to your heater , dont just tee off a nearby rad

I am using the pipes from the original double 1m by 1m radiator

 

[townfanjon]

I am using the pipes from the original double 1m by 1m radiator

Yep that will do

 

[Lucky245]

Yep that will do

Still hasn't answered original question though. Pipes are 1.5m from position of intended new heater site. When (how close) should I pipe before upscaling to the 15mm pipes for the unit. (No Sarcasm intended)

 

[Harvest Fields]

So I presume that you do not have a kick space heater at the minute then?

 

[Lucky245]

So I presume that you do not have a kick space heater at the minute then?

Correct kitchen is being installed in 3 weeks so would like it fitted to allow fitters to work around pipework

 

[Harvest Fields]

If the manufacturers instructions say it needs 15mm pipe runs to work efficiently I would not pipe it in 10mm. But then that's just me

 

[Lucky245]

If the manufacturers instructions say it needs 15mm pipe runs to work efficiently I would not pipe it in 10mm. But then that's just me

I have read many threads on here saying people have had no problems with 10mm systems running plinth heaters, although equally people suggesting it wouldn't work. So I have 2 choices take a chance or have no heating in kitchen at all. Radiator was always piping hot so guessing flow wouldn't be an issue albeit it will be reduced in unit hence my logic (maybe misguided) to go for higher output device with assumption of loss of actual output. Suggesting she removes a unit from kitchen to fit another radiator may involve me moving out

 

[Harvest Fields]

Not that it will not work. It just may not work that well and you would need to throw the warranty out of the window.

 

[Lucky245]

Not that it will not work. It just may not work that well and you would need to throw the warranty out of the window.

Totally agree with warranty being useless but in my experience after first few weeks they are useless anyway as company will always make some excuse why they won't honour it. Like hep, Pipes and 25yr guarantee totally worthless. I also understand that assuming it works it won't work to advertised levels as I'm using smaller diameter pipe and therefore less flow hence my concept of over powering system in hope of being close enough. My only main question is if I upscale from 10mm to 15mm at 2m away will this be better than upscaling at unit placement?

 

[steadyon]

Why not just run 15mm from the heater to somewhere which will be accessible after the kitchen is fitted, then join to 10mm. If it doesn't work well, you could then extend the 15mm back to the manifold, and tee into the flow and return pipes which feed the manifold.

 

[Lucky245]

Why not just run 15mm from the heater to somewhere which will be accessible after the kitchen is fitted, then join to 10mm. If it doesn't work well, you could then extend the 15mm back to the manifold, and tee into the flow and return pipes which feed the manifold

I'm assuming from this that it makes no difference so I will run from current radiator 10mm toheater using 15mm. Thank you. Manifold would have been my preferred option but her in doors didn't want visible pipework up the walls as currently all the 10mm pipework runs under the floors (it's a bungalow) and that's been tiled over so via loft would be only option. I'll give it a go and see how we fair. Thanks

 

[Harvest Fields]

Because the manifold is probably all 10mm inlets and outlets. If it were my house I would trace the pipes to the manifold fit a new 15mm manifold with reducers to all the radiators and come off the new manifold in 15mm for the kick space heater. But then again, as stated in previous threads, that's just me.

 

[JCplumb]

As far as heat output is concerned you've already battered it by having any 10mm at all in the run between heater and flow/return pipework. You might squeeze a smidgeon of extra heat out if you maximise the 15mm but as said above, and as you already know, it won't perform brilliantly, but it might be alright if you're willing to take a punt.
If possible run 15mm from flow/return pipes, if not possible then as much 15mm as you can.

 

[Chuck]

It largely depends on information not given so far, including the length and configuration (bends, fittings, etc.) on the 10mm section. Replacing, for example, 10% of a run of 10mm tubing with 15mm tubing is not going to make a useful difference. Replacing 90% might do. As a rule of thumb, one can transfer up to 4kW via a 10mm tubing. A double panel 1 m x 1 m radiator can dissipate about 2kW.

It's not too difficult to do the calculations, given enough details, but if you prefer practice to theory and making a mistake is potentially costly an experiment might be worth considering. Something along the following lines perhaps:

The existing 1m x 1m radiator seems to have fairly similar power rating to your new one so open its TRV fully and check and adjust the flow and return tempatures in the usual way, say 65/55 (i.e. deltaT = 10°C). Now unhook the rad and temporarily reconnect it with 10mm using lengths equivalent to the final setup (include adjustments for fittings and bends). Check that you can still get acceptable F/R temps (i.e. deltaT = 10°C). If you can't get good F/R temps you'll need to use 15mm tube. If you can, but only just, it's a bit marginal. If opening the lockshield allows you to get F/R of say 65/60 (i.e. deltaT much less than 10°C) then you shouldn't have a problem.

Obviously, the closer you can make your experiment to the final setup the better, maybe use the actual new heater for the test, but it won't have to be perfect for you to get a good idea as to whether you'll have a problem or not.

 

[Lucky245]

It largely depends on information not given so far, including the length and configuration (bends, fittings, etc.) on the 10mm section. Replacing, for example, 10% of a run of 10mm tubing with 15mm tubing is not going to make a useful difference. Replacing 90% might do. As a rule of thumb, one can transfer up to 4kW via a 10mm tubing. A double panel 1 m x 1 m radiator can dissipate about 2kW.

It's not too difficult to do the calculations, given enough details, but if you prefer practice to theory and making a mistake is potentially costly an experiment might be worth considering. Something along the following lines perhaps:

The existing 1m x 1m radiator seems to have fairly similar power rating to your new one so open its TRV fully and check and adjust the flow and return tempatures in the usual way, say 65/55 (i.e. deltaT = 10°C). Now unhook the rad and temporarily reconnect it with 10mm using lengths equivalent to the final setup (include adjustments for fittings and bends). Check that you can still get acceptable F/R temps (i.e. deltaT = 10°C). If you can't get good F/R temps you'll need to use 15mm tube. If you can, but only just, it's a bit marginal. If opening the lockshield allows you to get F/R of say 65/60 (i.e. deltaT much less than 10°C) then you shouldn't have a problem.

Obviously, the closer you can make your experiment to the final setup the better, maybe use the actual new heater for the test, but it won't have to be perfect for you to get a good idea as to whether you'll have a problem or not.

As I only understand half of your technical explanation (which is too comprehensive at this time of night) I will try and add some supporting information.

As for length of 10mm piping I can only surmise this information based on following. House is a small 2 bed bungalow with 1 living room, kitchen and bathroom. The floor is wooden (not concrete) with new laminate flooring on top except kitchen and bathroom which are tiled.

Working on the knowledge that the 10mm piping is all sub surface as it does not run through loft. The hotpress has 22mm pipes bringing hot water from boiler 5m away to hotpress and is a pressurised system (not combi). The kitchen radiator was only 1.5m from hotpress and was always second radiator to become piping hot after the hallway one which was less than 1m from hot-press. The new heater will be roughly 1.2m from the radiators original position. Hopefully at this point with no need for angle joints (e.g. No 90 degree joints) but only a continuous length of piping.

Radiator was always very hot when fully open and as mentioned previously was a double panel and About 1m wide x 1m high. Around 5500 btu's if I recall correctly.

Hope that helps

 

[Chuck]

As I only understand half of your technical explanation (which is too comprehensive at this time of night) I will try and add some supporting information.

Incorporating your new information:

You are going to add the equivalent of about 2*1.5m (some allowance for the joints) of 10mm to the existing circuit.

5500 BTU/hr is ca 1.6kW.

With a typical circulating pump operating at say 0.3 bar (3m head) You can have a maximum of 10 m of 10 mm tubing, i.e. 5m flow and 5m return and still get maximum flow (0.091 kg/s, i.e. 4.2kW for deltaT = 11°C at the radiator and deltaP = 0.3 bar around the circuit).

I think you'll probably be okay just using 10mm to connect the new heater. If you want to be sure, however, you either need to provide more details about the pipework circuits or do an experiment along the lines I suggested.

If you want to be safe but ugly use 15mm. If you want to be neat and take a modest risk use 10mm. If you want to reduce or eliminate the risk do the experiment.

Personally, I'd do the experiment, but you should wait and see if others have any better ideas (or can spot flaws in my logic or numbers) before deciding.

Good luck

 

[Gasinspect]

If radiator was piping hot on 10mm, then so should the plinth heater. Manufacturers output calculations for radiators and plinth heaters are based on same parameters. Remember the systems on 8mm!! Look inside a thermostatic radiator valve and the size of the waterway is not even 8mm in many of them. So a short run of 10mm without sharp elbows should not reduce output, any more than it would for a radiator