balancing radiator, old subject but question

happyhero

Hi I have read loads on balancing and think I understand it quite well but I still have a problem.

Boiler is on 2nd floor (attic conversion) and I fitted a large upright radiator (7000BTU's) on ground floor. I ran 22mm as far as possible and last 2 meters or so in 15mm. All rads have thermostatic valves fitted except bathroom towel rad.

It seemed to work fine but now is only luke warm, now that weather is getting colder, so I read and started on balancing.

Main problem is that I am struggling to build up a 11 deg C temperature difference between flow and return on the other two on the ground floor. If I do nothing I find flow and return temperatures are very close. I find I have to virtually close the lock shield valve to achieve this 11 deg C difference and then the the rad doesn't seem to get as hot and the room doesn't really get warm even though the rad is still quite hot.

When balancing what percentage would you say the valve should be open? I know it will vary but can you give me a ball park figure because I read somewhere that it may be around the 50% mark whereas, as I said I am having to virtually shut down the lock shield valves to get the ideal 11 deg C.

Should I expect it to be nearly closed or open about a turn or so?

Any help appreciated.

uncle_buck_3

Balancing radiators is all well & good in theory but in practice you quite often end up with problems.

A lot of the time when you close down the lock shield valve it starts to make an unacceptable noise….so you have to open it until the noise goes away (this is with top of the range valves) so count that one out!

I would advise you to throw away your pipe thermostats & adopt the “Common sense balancing principal”
....which is ….close down the rads that are close to the boiler as much as you can without them becoming noisy….then as you work your way from the boiler leave the rads open a bit more.
Any problem rads will soon show up (not heating the room etc) & you can rectify these as you go.

To be honest with you balancing heating systems isn’t really that necessary now a day with the introduction of 2 pipe & manifold systems….it was very necessary with the old single pipe systems that were fitted in the 70’s! ….so don’t pull your hair out trying to achieve the perfect balanced system …. because in my experience it doesn’t exist!!

HTH

andrew-b

Even if you balance the system surely the TRVs turning individual rads on/off ( as the temperatures in each room vary) will unbalance the system (as a whole - rather than single rads) again?

Andy

Avoriaz

I’m confused.

If all your radiators are fitted with thermostatic valves, how and why are you balancing the system? Surely that is precisely what the thermostatic valves do for you automatically.

The only balancing you need to do is find the right setting on the valve for the room it is in. In theory, if they are all identical, they should all be calibrated identically but you might want to set some rooms hotter than others.

As far as I am aware, you fit the thermostatic valve on the supply/flow side of the radiator and fully open the lock valve on the return side and then turn the thermostatic valve to the setting required. Forget about trying to get an 11C degree difference, the thermostatic valve controls the flow for you. If you have closed the return valve almost completely it is no surprise the room is cold.

I apologise if I have missed the point.

andrew-b

Avoriaz wrote:

As far as I am aware, you fit the thermostatic valve on the supply/flow side of the radiator

Depends on the TRV...we had two TRVs fitted in the bedrooms when we had our new boiler that can be fitted on either flow or return (twist to set one way or the other).

Andy

david29dpo

i thought the point of balancing was to get all the rads hot at the same time.?

ariba10

Thermostatic valves will not balance a system.

If you want to balance with thermo valves fitted I would think it would be better to do it with them fully open.

happyhero

Avoriaz wrote:

I’m confused.

If all your radiators are fitted with thermostatic valves, how and why are you balancing the system? Surely that is precisely what the thermostatic valves do for you automatically.

The only balancing you need to do is find the right setting on the valve for the room it is in. In theory, if they are all identical, they should all be calibrated identically but you might want to set some rooms hotter than others.

As far as I am aware, you fit the thermostatic valve on the supply/flow side of the radiator and fully open the lock valve on the return side and then turn the thermostatic valve to the setting required. Forget about trying to get an 11C degree difference, the thermostatic valve controls the flow for you. If you have closed the return valve almost completely it is no surprise the room is cold.

I apologise if I have missed the point.

Yes I would agree with what you say more or less but unless I reduce the flow in some of the other ground floor rads the new large one doesn't get hot and so doesn't warm the room. I think the idea of balancing is to insure a strong flow to the radiators that are further from the boiler, so if you make it so the water cant travel through the others on that floor, it takes the easier route and thus heats up my big one to hot, and of course if you get this right they all heat up. I think its a bit like the hot water is biased to the easiest route and you have to make it find all route of equal ease, if that makes any sense.

It is annoying as really you just want to do what you say, regulate each room with the rad stat and open the lock sheild valve fully so that it does the job of managing the temperature in each room for you. But at the moment my ground floor hall one and lounge get hot but my dining room one only gets warmish. If I close the other two off completely the dining room one gets hot.

Avoriaz

In that case, either your pump is not powerful enough, the boiler is under rated for the house or the c/h system is badly designed or faulty.

Check your pump and see if you can turn it to a higher setting.

You can’t increase the BTU output of your boiler but you can turn up the output temperature of the water and that might help.

If neither of those work, maybe there is an airlock affecting flow to the furthest rads.

You really should not be closing the lock valves on some rads to force the water to the more distant rads. That defeats the whole point of TRVs.

silvercar

I had a problem with the furthest radiators not heating up. I too thought it was a balancing problem. someone suggested it could be an air lock or sludge. I turned all the other rads off one by one until only the cold ones were left on; this shifted the problem and now they all work fine.

uncle_buck_3

david29dpo wrote:

i thought the point of balancing was to get all the rads hot at the same time.?

That’s exactly the point of balancing a CH system.
In an ideal World the boiler would be in the centre of the CH system with equal distances of pipe to each radiator…each radiator would then receive the hot water at the same time & they would all heat up together. Unfortunately this is never the case…some radiators are close to the boiler while others are far away….hence balancing the system. Closing down the lock shield valve a little on the radiators close to the boiler encourages the hot water to find its way to the far away radiators quicker.

Avoriaz wrote:

You really should not be closing the lock valves on some rads to force the water to the more distant rads….

I disagree…..that’s the whole point of balancing a CH system.