Lockshield Valves

[skylined_gtr]

Hi all

I am asking questions like there is no tomorrow sorry about that!

Lockshield valves. I have found a guide on the web that says to balance them you need to:

1. Open the lockshields and TRV's on all the rads.
2. Switch the heating system on.
3. Find the rad that heats first.
4. Check the temps on the pipes heating that rad, there should be a 12 deg temp difference, adjust the lockshield to make that so. (I used a digital laser/infrared thermometer)
5. Move on to the next rad and repeat the process.

So I did that, set the central heating thermostat to 30 deg (so the boiler wouldn't switch off during the process) and went about adjusting the rads.

Adjusted the first, moved on the the next then the next and so on. Went back to check the first and it seemed to be different to the 12deg I difference I set it to.

Is this normal? Should I expect this as I have adjusted others then come back to check from the beginning and should I re-adjust if it has changed? Not sure if I need to start the whole process again!

Thanks!

 

[skylined_gtr]

P.S. I read another post on this forum that gave this procedure for balancing the lockshields:

Balancing procedure:

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. Attach the pipe thermometers to the first rad in the list made in step 5 and open the LS valve a quarter turn
12. Wait until temperature has stabilised on the two thermometers. 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.
13. When you are happy with the first rad, move on to the next on the list.
14. Repeat steps 11, 12 and 13 for each rad on the list.
15. When you have reached the last rad, check the boiler temp difference and adjust pump speed if necessary.
16. Go back to the first rad and test it is still giving the correct difference
17. 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
18. Replace TRV heads and set to required temperature


This seems a better way to do it to be honest but I have a couple of probs with the above:

Step 6 - What is the bypass valve? I have an electronic diverter valve is that the same thing?
Step 7 - I don't know what the temp difference should be for me boiler? I have a Thermoecon oil fired boiler and a Grundfos Superelectric central heating pump.

Anyone have any thoughts on this?

 

[D_Hailsham]

What is the bypass valve? I have an electronic diverter valve is that the same thing?

The bypass is not the diverter valve.

Do you have a pipe, tee'd off after the pump but before the diverter valve, with a valve on it which connects to the return pipe? If so, this is the bypass valve. It allows some of the water to feed back to the boiler. You usually find them on low water content boilers.

I don't know what the temp difference should be for my boiler? I have a Thermecon oil fired boiler

Ask the manufacturers, GAH! Tell them the full model no, including the GC number. If you have a bypass, ask them about that as well.

01394 421 160 or [email protected]

 

[bengasman]

first of all, bypass should be automatic and set properly before starting the rest of the job
when you have that sorted, a far better way is to close all the ls valves and open them halve a turn, and then start the boiler

 

[skylined_gtr]

I have a Megaflo hot water cylinder and I think I know the pipe you are talking about.

If I close all the lockshields and open them all halfway won't that create a huge imabalance?

I want to make sure the rads are working properly as the house has never been 'warm' as such, since I have been playing with the lockshields it seems to be getting warmer.

I would like to know which of the 2 different versions of lockshield balancing you would use? ...and if once you set a lockshiled valve you should recheck it again a day or so later to check there is still an 11/12 deg difference.

Thanks for the advice guys, will also contact the manufacturer

 

[D_Hailsham]

If I close all the lockshields and open them all halfway won't that create a huge imbalance?

Yes!

The typical LS valve will have 3-4 turns between closed and open but, due to the design of the valve, their flow/opening characteristic is not linear; i.e closed = 0% flow, half open = 50% flow, fully open = 100% flow. The typical LS valve will provide full flow when it is about 1-1½ turn fully open. So, if you open all valves half way, they will effectively be fully open.

The amount a LS valve has to be open depends on the wattage of the radiator and the pressure difference across the valve. The higher the pressure difference, the less the valve has to be open; the lower the wattage, the less the valve has to be open. Radiators close to the pump will have a higher pressure differential, so the LS valve will have to be open less than those further away. But a 500W radiator will need the valve open less than a 2000W radiator in the same position.

I want to make sure the rads are working properly as the house has never been 'warm' as such, since I have been playing with the lockshields it seems to be getting warmer.

Shows you are doing something right.

I would like to know which of the 2 different versions of lockshield balancing you would use?

The first one of course! But then I am biased as I wrote it.

if once you set a lockshield valve you should recheck it again a day or so later to check there is still an 11/12 deg difference.

Not really necessary, but no harm done.