Central heating-rads hot downstairs only luke warm upstairs!

Guys,

I have a Vokera compact 28 boiler in my 4 bed detached house, we've recently extended the house to give us the 4th bedroom.

Upstairs all the rads are luke warm at best even with the flow valve wide open, downstairs the rads are all very hot to touch.

The exception is the rad in the extension upstairs which gets as hot as the ones downstairs.

I deduce from this that the extension is on a new feed independant from the old pipework feeding the old part of the house downstairs and up.

I've even tried closing off all the rads downstairs in the old part of the house to try and get the hot water up to the luke warm rads upstairs but it made no difference whatsoever.

I've had a go at balancing the system but this seems pointless if I can get the upstairs rads hot with the downstairs 'old' rads off (i'm assuming the new rads downstairs are on the same circuit as the new rad up)

Any ideas what is causing this too happen - my poor little lads room is freezing yet downstairs the house is toast.

Please help me out here as this is driving me mad now - I guess i'll need to call a plumber out unless anyone can trhrow any light on this one....is the boiler struggling to pump the water ? (if so why is the new upstairs rad ok ?)

The boiler is about 6years old and the rads upstairs about 3 years old.

Many thanks in advance,
Mike.

mikeyw said:

Upstairs all the rads are luke warm at best even with the flow valve wide open, downstairs the rads are all very hot to touch.

The exception is the rad in the extension upstairs which gets as hot as the ones downstairs.

I deduce from this that the extension is on a new feed independent from the old pipework feeding the old part of the house downstairs and up.

Click to expand...

Presumably the upstairs heating was OK before you built the extension. If so, get the builder/plumber back to sort it out.

Ask the person who did the extension to your heating system where he connected the new radiator.

What "flow valve" are you talking about? Where is it located?

I've even tried closing off all the rads downstairs in the old part of the house to try and get the hot water up to the luke warm rads upstairs but it made no difference whatsoever.

Click to expand...

Did you also close the rad in the extension upstairs?

I've had a go at balancing the system but this seems pointless if I can get the upstairs rads hot with the downstairs 'old' rads off (i'm assuming the new rads downstairs are on the same circuit as the new rad up)

Click to expand...

Don't understand why you think it is "pointless". Also, are you saying that your extension has radiators downstairs as well as upstairs and these could be on a separate circuit from the rest of the house?

D_Hailsham said:

Presumably the upstairs heating was OK before you built the extension. If so, get the builder/plumber back to sort it out.

Ask the person who did the extension to your heating system where he connected the new radiator.

Click to expand...

The Job ended on bad terms so no come back there

What "flow valve" are you talking about? Where is it located?

The shut off valve on the end of the rad that controls flow

Did you also close the rad in the extension upstairs? - No

Don't understand why you think it is "pointless". Also, are you saying that your extension has radiators downstairs as well as upstairs and these could be on a separate circuit from the rest of the house? - yes i believe it must be the case[/i]

Any further thoughts guys ?

mikeyw said:

The shut off valve on the end of the rad that controls flow

Click to expand...

Rads have two valves: a wheel or thermostatic valve and a lockshield (for balancing). I presume you mean you had the wheel/thermostatic valve wide open.

I suspect that the rads in the new extension are grabbing much of the heat due to the way they have been added to the circuit. You should be able to resolve this by proper balancing.

Balancing procedure:

You will need either two clip on pipe thermometers (£12 each) or an infrared thermometer (about £30 from Maplin). I have used both and prefer the infrared as it has a faster response, is more accurate and can be used for other things, e.g checking the temperature distribution over the surface of a rad.

1. Turn boiler off and allow to cool
2. Make sure HW is turned off
3. Open all LS valves fully; remove all TRV heads and open all manual rad valves fully.
4. Turn the boiler temp to max and bring system up to temperature.
5. Check, by feel, the order in which the rads warm up and make a list.
6. Adjust the bypass (if fitted) as per mfr instructions
7. Measure the temperature differences between the flow and return pipes at the boiler. What it should be will depend on the boiler -refer to the installation manual. If the temperature is not right, you need to adjust you pump speed (higher speed gives smaller difference and vice versa). Set the speed to give as a difference as close to the mfrs recommendation as possible.
8. Turn the boiler off.
9. Close all lockshield valves. Leave TRV heads off.
10. Restart boiler
11. Go to first rad in list made in step 5
12. Attach the pipe thermometers (if used) to the flow and return pipes near the rad valves and open the LS valve a quarter turn.
13. Wait until temperature has stabilised on the two thermometers (or use the IR thermometer to measure flow and return temp in the pipes adjacent to the valves). If the difference is smaller than that at the boiler, close the LS valve a fraction, or vice versa. Wait until the temp has stabilised and check again.
14. When you are happy with the first rad, move on to the next on the list.
15. Repeat steps 12, 13 and 14 for each rad on the list.
16. When you have reached the last rad, check the boiler temp difference and adjust pump speed if necessary.
17. Go back to the first rad and test it is still giving the correct difference
18. And so on, going round and checking the temperature difference until they are all as near the required drop as you can make them. Don't expect perfection
19. Replace TRV heads and set to required temperature

A very small change in the amount a LS valve is open can have a considerable effect on the temperature difference. Because of the way LS valve are constructed, it is virtually fully open when it is one and a half turns open. So most adjustment will be within one turn from closed.