TCV's on rads and system balancing????

gorwanvfr

Ok here goes. If I fit TCV’s to all my rads but one. How does the system remained balanced??
If you read about balancing a system every rad gets just the amount of water it needs to heat all of them to the same temperature. i.e. the rad closest to the boiler gets a lower flow then the rad furthest from the boiler. So they all end up at the same temp.
How does this work with TCV’s fitted

Joey the lips

You dont fit TCV's to every rad you fit TRV'S to every rad. Also your not ment to completly turn a trv off your ment to turn it no lower than the snowflake.

Why do you want TCV's on every rad and why do you feel the need to question the system.

Are you sure you ment TCV'S

gorwanvfr

Joey the lips wrote: »

You dont fit TCV's to every rad you fit TRV'S to every rad. Also your not ment to completly turn a trv off your ment to turn it no lower than the snowflake.

Why do you want TCV's on every rad and why do you feel the need to question the system.

Are you sure you ment TCV'S

Sorry about my terminology meant to say TRV’s
I believe you fit them to every rad except one so when all the TRV’s are closed you still have circulation through one rad so not to dead head the pump.
What my question is how do you maintain the balance of the system. Since if the house is cold and the heating is turned on all the TRV’s will be open.

Joey the lips

gorwanvfr wrote: »

Sorry about my terminology meant to say TRV’s
I believe you fit them to every rad except one so when all the TRV’s are closed you still have circulation through one rad so not to dead head the pump.
What my question is how do you maintain the balance of the system. Since if the house is cold and the heating is turned on all the TRV’s will be open.

Your not making sense. Have you a specific problem? ie all your rads are cold but your boiler is on???

Pete67

To answer your specific question, you balance the radiators with the lockshield valve, not the handwheel one which will be removed if you install TRVs. There is usually a plastic cover which covers the valve stem, remove it to adjust.

If you install an automatic bypass valve between the flow and return primaries then you will not need to worry about a bypass radiator. Honeywell make a good one:

http://content.honeywell.com/uk/homes/Catalogue/Non%20Electric/5.1%20DU145.pdf

and

http://europe.hbc.honeywell.com/products/ecatdata/pg_du145.html

The auto bypass valve maintains a constant head to the radiators and flow through the boiler even when the TRVs are all closed, which improves the operation of the system greatly when TRVs are used. It also prevent the boiler and pump from being 'dead-headed'.

I would set the auto bypass valve to approx 0.3 bar, then go around and remove the heads from all the TRVs and balance the rads in the normal way. Set the boiler thermostat to max and adjust the lockshield valves on each radiator to get a 10 degree C drop across each radiator. If it's a condensing boiler, use 15C drop, this will result in less flow through each radiator, but the system should be designed to take account of this by using slightly larger radiators.

If you can't get all radiators heating together you may need to increase the auto bypass valve setting. Don't forget the coil in the cylinder, too much flow here will starve the radiators. Aim for a 10C drop across the coil but you can only check/adjust when the cylinder is cold as otherwise there will be little or no temp drop across the coil.

Reinstall the TRV heads when done and adjust each to maintain a comfortable temperature in the room. You should aim for 20-21C in living rooms and 17-18C in bedrooms.

It gets a bit more complex for a zoned system, basically you should not use a TRV in a room which has a room thermostat controlling the boiler or a zone valve directly.

gorwanvfr

Thanks a million "Pete67" your answer is perfect and just what I was looking for and confirmed what I was thinking. Never knew about the pressure control valve sp will have to get one when I get my 29 TRV's.

Pete67

you're welcome