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JamesI, Developer
Category: Home Improvement
Satisfied Customers: 1346
Experience:  I have a portfolio of renovated houses, including DIY projects from installing bathrooms and new heating systems to rewiring.
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Radiator/piping problem

Resolved Question:

I have installed a radiator in a new garage I have had built, and I have tapped into the existing house heating circuit to supply it. The house piping is 15mm, but I have used 10mm plastic coated copper for the new radiator, which is 30ft away from the nearest house radiator. The pipes go underground, the plastic coated copper is inside blue alkathene, which is inside a 4" plastic conduit pipe. The new radiator is fitted with a Danfoss bi-directional valve. On powering up the system after the installation , although I can get water appearing at the bleed valve on the new radiator I cannot seem to get hot water to flow. Have I made a mistake by using the 10mm pipes, or is there something else I have missed? The pipes at the house radiator get hot, and I have closed off the radiator which I though would have directed all the flow through the Tees to the garage, but still no heat. Given the high ambient temperature I cannot believe I am losing all the heat in the 30ft distance, and I assume that I am not getting a proper flow. I took a Tee from the supply to the house radiator to the garage, and Teed the return from the garage into the return from the house radiator. I have bled all the house radiators, and I have tried the bi-directional valve on the garage radiator in both positions but to no avail. Water is obviously in the system as it appears at the garage radiator bleed valve, but the garage pipes remain cold. HELP!

Submitted: 2 years ago.
Category: Home Improvement
Expert:  JamesI replied 2 years ago.
Ok, its very unlikly your loosing 20 degrees of heat in 30ft.

First of all, take the inlet side witht eh Danfoss valve and open it so some water goes into a bowel then see if the water is hot.

Then do the same on the other side (outlet) and see if either is hot to touch.

This rules our an issue eg air blockage with the radiator.

Your most likly having issues due to using 10mm pipe as what your using probably has a core nearer 7mm by the time you put the gromits in around the joints etc.

So this means you probably need to adjust the outlet on the other radiators to restrict water flow, to increase the flow rate going to your radiator in the gargage.

Are you sure you have T'd off the boiler feed and return, and not spured on from another radiator?

Let me know how you get on, and remember to keep the system topped up if using a pressurised system.
Customer: replied 2 years ago.

I have taken a T from the supply and return to the nearest house radiator, not from the boiler although presumably these pipes come from and go back to the boiler.

When I installed the new radiator I arranged it so that the Danfoss valve was on the supply side (as I thought). I had assumed that the house radiator had been installed so that its valve was on the supply side, however last night after turning on the system I noticed that the return pipe from the house radiator was hot whereas the pipe to the valve was cold, so it may be that I have put the Danfoss on the wrong side of the new radiator, however the leaflet that comes with the valve says it can be fitted to either side and I have therefore left it where it is, but experimented with the adjustable flow control bit of it, without seeing any difference.

As I already said, I had turned off the house radiator in order to try to get more flow to the garage, but to no avail. This I did not understand since the house radiator pipes were hot, and shutting off that radiator should have meant all the flow was now going down to and coming back from the garage through the 10mm branches of the T couplings in the pipes to the house radiator.

The garage is uphill about 2 or 3 feet from the house radiator and I obviously got some air at the bleed valve when I initially filled the system. Since then I have bled about 3 litres of water from the bleed screw in order to try to get warm water through it, but got no more air (and no hot water!).

The Danfoss valve itself has quite a restricted passage through it, so I doubt if it would pass much more than the 7mm bore of the 10mm pipe. I gather that 10mm is frequently used in modern installations anyway, so am puzzled as to why it doesn't seem to work for me.

It's not a pressurised system- there is a header tank in the house loft.

If I need to take a supply from the boiler this would be very difficult and would involve long pipe runs as the boiler is in the kitchen which has a concrete floor whereas the pipes to the room radiators run under the floorboards. I can see no easy way of accessing the boiler direct from the room where the pipes go to the garage. I do not know how the original installation gets from the kitchen/boiler to the room radiators, perhaps bored through brick walls below the floor of the adjacent room straight into the kitchen, although the kitchen concrete floor is on the same level as the room wooden floors?

I'll open the pipes at the garage radiator as you have asked, but since I am getting water but not any air at the garage radiator I'm not sure what this will achieve, however I'll certainly try it later on this evening and see if I can tempt some hot water to arrive in the garage!

Customer: replied 2 years ago.

Second reply...

I think I've solved the problem. I have been a plonker and connected both new pipes into the same original pipe. The pipes cross over below the floor and I have been working upside down looking through 2 removed floorboards... that's my excuse anyway! I am sure that when I re-make the connections properly tomorrow all will be well. Thanks anyway.

Expert:  JamesI replied 2 years ago.

First of all you dont need to take the feed off at the boiler, the boiler central heating look should run through the entire house, normally 22mm dropping to 15mm in places.
You just need to make sure the feed you have T'd from is off this main run and not a spur off a radiator, as I suspect you have taken a feed from another radiator, so if the radiator is switched off you may only have one side of unrestricted flow.
Normally you put the valve on the inlet to stop hot water bleeding into the radiator, as convection would cause the radiator to heat even if it couldnt freely flow.
That said it shouldnt matter in terms of getting heat to the radiator which way round the pipes are for now.
By opening up the pipes I would flush some water through and see what your flow rate is like if after 2L the pressure is dropping its suggesting you need to revisit wher eyou have taken the T. What I would be looking for is where the existing radiator in the living room is T from.
Most houses use microbore which is 8mm, and most new houses use the 10mm you use so I dont think its a pipe issue, by in large its more rated by the size of the radiator panel.

Expert:  JamesI replied 2 years ago.

Just seen your second post, this sounds exactly like the problem.
As my post above suggests you dont need to worry about taking a feed from the boiler just make sure its on the feed and return, and not in series between two other valves which can cut off the flow to it.
Please get in touch if you still find issues, but think you are on to a winner.

I would appreciate if you can rate the level of service you have received today.

Have a good evening

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