15mm Rad on 10mm pipework ?

[vman298]

Hi All.

I need a little advice around a radiator replacement I am contemplating.

I currently have a towel radiator off 10mm feeds in my kitchen. We have extended the kitchen and now it is not really up to the job. Putting the kitchen dimensions into an online tool shows I need a radiator that can output over 7000 BTUs.

Have been looking at the designer rads, the Milano Aruba Plus is the current favourite, but I am struggling to find an answer as to if it will work as it needs a 15mm feed. I have read about reducers, and can see how that would reduce the flow into the radiator, but cant find anywhere which explains what the impact will be - will it be that the rad will only work to 66% efficiency, or just slow to warm up or not work at all etc

I asked a plumber friend and he is not sure if it would work and rates the chances as 50/50 which doesnt help, so am reaching out to a wider audience 🙂

The house is 17 years old and I have been told by a few folk over the years that my radiator feeds are 10mm.

If there is a chance that this doesnt work, can anyone experienced in these things point me to a radiator (tall, slim type) that takes a 10mm feed that has a high BTU rating.

Thanks

V.

 

[bigads28]

You wouldn't even notice the difference. The holes through the valves are nothing like 15mm and they get closed down to balance the system.

Put it in you'll be fine! :sorcerer:

 

[SimonG]

As long as the 10mm pipework wasnt teed off some more 10mm you should be ok. Is the feed to the existing towel rail via a manifold or larger pipework i.e 15mm or 22mm.

 

[woodytheplumber]

I was allways told 10mm upto about 6500 btu max but I also agree with ads if the pipework is in place chances are it will work but if you can run a 15mm flow and return back it will be better

 

[Best]

It depends also if the 10mm pipes are run a long distance. If they are several metres long (down walls or below floors) until they reach the rad, then the pipes will have a big resistance and flow will be reduced. A rad valve inside having a very small orifice or closed down to balance a system, will reduce flow, BUT NOT the same as several metres of a small bore, which can reduce flow badly and permanently!
Those designer tall radiators need IMO to have a bit of force and good flow up to them, for the rads to heat properly. You will need the system ballanced well and consider replacing the 10mm to 15mm back as far as you can, if possible, because that reduces the length of restrictive pipes. Hopefully you get lucky and the rad works fine, but remember it is when there is high heat loss of the rad in severe winter that will test the pipework flow to the rad.

 

[vman298]

As long as the 10mm pipework wasnt teed off some more 10mm you should be ok. Is the feed to the existing towel rail via a manifold or larger pipework i.e 15mm or 22mm.

Problem I have is that I have no idea. The way the house is laid out, the boiler is upstairs and the pipework to the kitchen radiator will be between 7-8m. There is a WC radiator on the other side of the wall to where the kitchen radiator is so I assume they will be sharing some of the pipework.

 

[vman298]

Those designer tall radiators need IMO to have a bit of force and good flow up to them, for the rads to heat properly. You will need the system ballanced well and consider replacing the 10mm to 15mm back as far as you can, if possible, because that reduces the length of restrictive pipes. Hopefully you get lucky and the rad works fine, but remember it is when there is high heat loss of the rad in severe winter that will test the pipework flow to the rad.

Thanks best and woody.

My thoughts initially was to look at going to 15mm, but the timing to do such work is not good at the moment. Best hit on another of my concerns around the the radiator as the high BTU one is 2m tall, so would the 10mm pipework provide enough force to fill it. However, Woody has put another idea in my mind and that is to look for a 6500BTU unit which may be smaller.

Thanks to all those who have responded.