balancing central heating system

[nairb999]

I have replaced a radiator in my hall with a larger unit for greater heat output. It has turned out really well. All the radiators get piping hot but I am having trouble
rebalancing the system. I have managed to balance systems before using simple
technique ie turning heat on full all TRV's fully open then run round the house ensuring all radiators heat up at the same rate (15 in total)

I now have a noisy system and have to bleed 2 radiators frequently. Would using radiator thermometers help. Also as I have a bypass radiator in the bathroom with 2 lockshield valves - should these be both fully open?

Any help would be greatly appreciated

 

[dcawkwell]

If you have an open vented system sounds like it is plumbed in badly and drawing air into the system.

Another possibility is you have a sealed system and the expansion vessel has lost it's charge.

The only reason the system is noisy is because there is air in it.

 

[nairb999]

it is open vented but did work ok before ie did not let in air

 

[dcawkwell]

it is open vented but did work ok before ie did not let in air

Have a look in your header tank. Maybe the system is pumping over through the vent pipe.

 

[nairb999]

took a look at header tank. Nothing untoward .
In my original post I highlited bypass radiator
should valves be fully open

 

[dcawkwell]

took a look at header tank. Nothing untoward .
In my original post I highlited bypass radiator
should valves be fully open

No the bypass radiator can be balanced like the rest.

Could be a blocked feed pipe and the system isn't topping up.
You bleed the radiator and this just robs water from other radiators
this when balances up as the pump runs around.

The other test to do would be to try and light the gas in the radiators.
If it goes off with a pop it is hydrogen caused by an
electrical fault.

 

[nairb999]

Thanks for all your suggestions. I wii try gas test tomorrow.
Can you assist me on how to balance bypass radiator. Should I determine whichh
is the input side then leave that fully open then adjust other side

 

[dcawkwell]

Thanks for all your suggestions. I wii try gas test tomorrow.
Can you assist me on how to balance bypass radiator. Should I determine whichh
is the input side then leave that fully open then adjust other side

Open one side of radiators fully usually right.
Then open the other side about 2 turns. Any radiators that are cold open up half a turn. Any radiators that are hot turn down half a turn.
Repeat if necessary. Sorted.

 

[nairb999]

Except for bypass radiator all radiators have TRV's. I presume you mean open
this fully. They are mostly on the left

 

[dcawkwell]

Except for bypass radiator all radiators have TRV's. I presume you mean open
this fully. They are mostly on the left

Yes. if you have a TRV open fully when balancing.

 

[nairb999]

Except for bypass radiator all radiators have TRV's. I presume you mean open
this fully. They are mostly on the left

Yes. if you have a TRV open fully when balancing.

I decided to order an infrared thermometer as I am having no luck balancing my system. Had a good read of the FAQ on this site regarding balancing and decided to give it a go with infrared thermometer.

First part flagged up an immediate problem. Opened all lockshields and removed TRV's then fired the boiler on max. Just about managed to get round all the radiators to see order and I was amazed to see the heating order was nothing like I was expecting ie the order did not tie up with distance from boiler eg the last 2 radiators could not have been further apart in the house.

By the time I completed this test I the checked the temperature difference between flow and return and was amazed to find the difference was in excess of 25 degrees. The boiler is a Potterton Prima 60F.

Went to the next step in the FAQ and it was pretty clear I was not going to get a difference of 11 degrees.

As the highest pump setting did not get it much lower does this suggest I have a pump problem.

 

[dcawkwell]

No wouldn't worry. If you boiler is reaching it's temperature and is coming off and on occasionally it is keeping pace with demand.

I would look at what the temperature difference is when the system is up and running for a while.

 

[nairb999]

No wouldn't worry. If you boiler is reaching it's temperature and is coming off and on occasionally it is keeping pace with demand.

I would look at what the temperature difference is when the system is up and running for a while.

Again many thanks for quick response. I have tried everything to get the system to run quietly. Failing miserably. The only time I have got the system to run quietly is when I have just had the last radiator on the circuit on its own. Boiler was set to max and tripped out after a while.

 

[D_Hailsham]

Which pump do you have?

 

[nairb999]

Which pump do you have?

Circulating pumps CP63. previously myson