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PostPosted: Fri Mar 24, 2017 10:53 am 
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Dear All

After a recent boiler repair where the system (pressurised combi) was emptied I was informed to have the CH system flushed to maintain the service contract. Added chemical cleaner to a radiator and ran system with chemical in for about 10 days. Flushed (not power flush) the system and each radiator several times until the water ran as clear as it ever will - what a palaver.

Since then, as expected really, the radiators and temperatures in each room are cock-a-hoop. I have bled the radiators thrice - last time this morning before taking the temperatures at both inlet and outlet side. I used a fire service digital thermometer and took the temperatures on the 10mm pipe leading to the thermostatic valve and from the lock shield. See temperatures below.

1) Are there any explanations for these very odd readings?

I have read the instructions for the "balancing act", but am not sure which method is the best/easiest to follow.
https://editorsean.com/articles/balancing-radiators-without-thermometers/
http://www.diyfaq.org.uk/plumbing/rad-balance.html
https://www.homebuilding.co.uk/how-to-balance-radiators/

Yours expert advice appreciated as always.

K


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PostPosted: Fri Mar 24, 2017 2:55 pm 
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The valves are the "wrong" way round on: Dining, Kitchen, En-Suite. (Cloak, Hall, might be wrong way round; too close to tell).

This doesn't matter; all balancing does is adjust the flow through the rad; what goes in must come out.

Were rads balanced with the TRV heads in place?

Is the "fire service" thermometer a contact type or infrared type?


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PostPosted: Sat Mar 25, 2017 6:45 am 
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DH, no idea how previous balancing was done or with/without TRV. Bought new 10 years ago and this is first flush and balance since.

Digital thermometer is the contact type, recently calibrated.


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PostPosted: Sat Mar 25, 2017 1:00 pm 
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Thanks for that info. If it was a new-build 10 years ago, I doubt if the heating system installers bothered very much about balancing the system - not paid enough by the main contractor to spend time on that, in any case systems with TRVs balance automatically (allegedly).


Here's a quick way to balance the system

1. Remove all TRV heads and wheel valves
2. Set all lockshield valves to half-turn open.
3. Set pump to middle speed - if possible.
4. Let the system warm up to normal flow temp (you may need to set room stat higher to keep boiler alight).
5. Measure flow and return temps at boiler and calculate difference. If below 10C, turn pump down; above 20C, turn pump (if possible)
6. Measure flow and return temps on the two radiator pipes for all rads; calculate difference; write all this down.


It's now a case of tweaking the lockshield valves to give approximately the same differential on all rads.
Never adjust by more than 1/12 turn at a time
A) Start with rad with greatest differential - open 1/12 turn will reduce differential.
B) Wait 5 minutes for the change to take effect
C) Check all rads to see what effect it has.
D) Repeat from A until you are happy with the results (Check boiler differential is still OK.)
E ) Replace TRVs and set to desired temperature. (NB setting to max does not heat the room up any quicker)



For this message the author D Hailsham has received thanks - 3: Kabous, sajeel, stevewestern
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PostPosted: Wed Oct 18, 2017 12:02 am 
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Thanks DH, I eventually followed your instructions to balance the radiators. Got them all within a 12°C differential except one 64° at one end and 44° at fully opened lock shield end. After 3.5 hours of adjustment I couldn't be Arsenal with this one.


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PostPosted: Wed Oct 18, 2017 7:22 am 
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A dumb question, but what does balancing a system achieve?
No one has ever explained it to me. I guess it makes things more efficient, but given that it may well take a few hours labour it would have to make a big difference to justify the cost, and I've never seen any plumber doing it..


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PostPosted: Wed Oct 18, 2017 8:02 am 
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It should make all the radiators heat up as quick as each other by restricting the flow to the ones closet to the pump and letting more flow go to those furthest away.

Water will always take the easiest route around pipe work.

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www.drlgas.co.uk



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PostPosted: Wed Oct 18, 2017 8:16 am 
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Thanks Dave, so not something to worry about too much unless you have problems with rads not heating up evenly.
I'll rest easy huddled in front of my fan heater..!


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