New Radiators Cold (pic diagram incl)

[Kenny1601]

Cant post pic so click here to see pic I drew up: diynot.com/forums/plumbing/new-radiators-not-working-pic-incl.376604/#2879186
Hi there.

Today I was over at my folks house as they have been having issue with new radiator that were fitted in there extension. When the heating is on, all the radiators in the house are roasting bar the two in the extension which are luke warm at best (inlet pipe to both radiators are roasting). The plumber has been back in numerous occasions but with no joy. I will try an explain what I have done as simple as I can so far.

Firstly I closed both valves on either side of the radiators and removed them and attached a hose on one end and cleared them both out. Refitted them and pressurised/bled and started the heating........no joy...still cold!
P.S. before I refitted I cracked open both inlet valves to radiators and got a good bit of pressure out them so happy that water is getting to them OK and as I said above, the I/l pipes are roasting when heating is on!

Next I shut the O/L valve I have labelled in my pic and both o/l valves on both radiators and split the pipe the O/L valve and a small dribble of water came out. when I cracked open the O/L from the main system.....lots of pressure as expected. I then split the coupling on both o/l valves of radiators and blew through the return pipes and both were clear.
Refitted everything and still no joy! 🙁

When the heating is on, the return pipe from the rad in the dining room is toasting but the return pipe from the extension is cold all the way to where it T,s into the main system.

So my next thought is the pressure coming back from extension is too low to over come the pressure on the main system and ends up lying in the return pipe?

So to over come this I thought removing one of the rad in the extension, so off to homebase and bought two 90 degrees bends, removed to two t-pieces I labelled 1 and 2 and fitted the bend.
Re pressurised, bled etc and nothing again! 🙁

Why is the pressure dropping so much over the rad's in the extension?
Would I be right in saying that the pressure appears to be too low on the return lines that it wont get back into the main ring at the t-piece.

p.s. even when I turn off both valves on dining room rad the return pipe from the extension all the way to 2nd t-piece is cold (2nd t-piece after the O/L valve.

Sorry this is long winded. But want to get as much info as I can.

 

[SimonJohns]

Your system requires balancing

Try turning off all the other rads in the house first and see if they get hot

If the answer is yes. You will need to balance the system

 

[tom609]

Your system requires balancing

Try turning off all the other rads in the house first and see if they get hot

If the answer is yes. You will need to balance the system

i agree with the above

 

[Kenny1601]

Hi SimonJohns, I have done this, the radiators do get warm but I can still touch them and hold onto them so not toasting as you would expect.

 

[SimonJohns]

Hi SimonJohns, I have done this, the radiators do get warm but I can still touch them and hold onto them so not toasting as you would expect.

Would I be right in guess that they have tee'd off the main pipe using a 10mm pipe and then split this in 2 to feed the rads?

 

[Kenny1601]

Its T'eed of onto 15mm pipe which is then T's off again to feed each rad. But I have since then removed the T's that feed the 2 rads and the one on the return line and fitted 90 degree bend so that only one rad is getting used and still no joy. Maybe I need to try equalising again?

 

[Ermintrude]

What sort of system is it? Turn off all rads but ones in extension , if they fail to heat up pipework is insufficiently sized? When balancing just open rads 1/4 of a turn. Let system settle then adjust again. All rads won't be same temperature when the whole system is on.

 

[Kenny1601]

The pipe work was 10mm but the plumber changed it all to 15mm lastweek but no joy.
He is now talking about moving the T piece that connects the two extension rads back into the main line, to further down the line ( towards the living room ) not sure what that's going to achieve??
is there a good guide on how to equalise??

P.S it's a one way combi

 

[Ermintrude]

Pm croppie he is really quick at typing it out.

 

[PlumbBobBob]

here you go thanks croppie i saved it as well

How To Balance Radiators
Tool List:

Radiator-bleeding key
Lockshield valve adjuster or adjustable spanner
Screwdriver
Digital thermometer or multimeter with thermometer function



1. Make sure all the radiators have been bled. Turn off the central heating and allow the radiators to cool.

2. Familiarise yourself with the valves. The lockshield will usually have a push-on cap or one that is secured with a screw through the top. Remove it.

3. Older models will have a wheelhead valve on the other side — used to turn the radiator on/off.

4. Newer radiators will have a thermostatic valve instead of a wheelhead valve.

5. Open up the valves on all the radiators in the house by turning them anti-clockwise.Wheelhead and thermostatic valves can be turned easily by hand, but the lockshield will need a plastic adjuster to open it up. These come with new lockshield valves. A spanner will also do the job.

6. Turn the central heating back on and note down the order the radiators heat up. Those nearest the boiler normally get hot first. If you’ve got a lot of radiators, get assistance. Turn the heating off and wait while the radiators cool down.

7. When the radiators are cool, switch the heating back on and go to the first radiator on your list. Turn the lockshield valve clockwise until it is closed and then open it by a quarter of a turn. Once the radiator has warmed up, take a temperature reading at the pipework leading to one of the valves.

8. Now take a temperature reading at the pipework leading to the other valve and open the lockshield valve gradually until there’s a 12°C difference between now and the reading you took in step 7 (allow a couple of minutes after each adjustment for the temperature to change). The temperature figures indicated in the last step and this one are relevant to the radiator shown – don’t take them as any kind of optimum figure – it’s the 12°C difference in temperature at the valves that counts. Next, check the rest of the radiators in the system following the order in the list. The further you move away from the boiler, you’ll find the lockshield valve will have to be opened more. The last radiator may need to have the lockshield valve fully open to work at full efficiency. Your radiators are now balanced and should work perfectly.

Getting A Temperature

A key part of this job is measuring the temperature difference across each radiator. Specially designed thermometers that strap round the pipes at either end of the radiator are available to buy or hire, but it’s not really necessary to use these. You can get away with a single digital thermometer — it just means that you can’t take simultaneous readings and you’ll have to move from one end of the radiator to the other.

Digital thermometers are available from around £10. Alternatively, some digital multimeters have a temperature sensor function. A digital multimeter with temperature function costs from £25 and can also be used for taking electrical readings and checking continuity in wires, among dozens of other functions.

 

[Dotty]

No worries Steve. Truth be told I stole it from somewhere. Can't remember where tbh!

 

[Kenny1601]

Brilliant lads!

i will borrow a heat detector from work and give this a try. I hope this is all it is and nothing major! Never heard if balancing a system before, is this only necessary when introducing new rads to the system??

thanks again for help!

 

[snowhead]

Never heard if balancing a system before, is this only necessary when introducing new rads to the system??

Needs to be done when system first installed
When any rads are added or removed.
When Radiators have been removed for decorating and both valves were turned off.
AND when someone has been meddling and messed up the Lockshield (return ) valve setting.

 

[Kenny1601]

God, every day is a school day! I always though the return valve was just a isolating valve to allow the rad to be removed!

going over tomorrow night so will update with results.

 

[Kenny1601]

Well equalising the system wasn't a success or shutting off every valve on every rad and leaving only the one in the extension open. The rad still stayed luke warm. . I am now starting to think that because the rads that are in the extension are Tee'd off from the rad in the dining room (15mm) which itself is Tee'd off the main 22mm pipe (same for return line), that's its dropping too much pressure??? \I have taken pics of the way the plumber has set it up but I cant upload pics via photobucket?

 

[BLOD]

Have you got a bypass valve ? if so try closing it a bit

 

[Kenny1601]

Daft question but where would this be located?? There are no valves in the pipes to and from the rads in the extension.

 

[Ermintrude]

Try bypass , it's been missed on jobs I've been to, it's normally a pipe bridging pump with a gate valve on it. Fully close then open 1/4 of a turn. U should hear water moving past valve if u put ear on it or close zones and hw but run boiler and pump bypass should get hot and flow and return at same temp quickly. Actually that's a pretty quick test. If system cold out boiler on full pelt. If after few mins boiler reaches temp / flow and return same temp but rads still cool ur bypass is open too much or if an auto set too low.