Draining radiators on a communal heating system

[erichsonb]

I have just moved into a block of flats with a communal heating and hot water system. It has a cold water tank in the loft and a hot water cylinder in the kitchen. I have a leaking radiator valve that I need to change. I've managed to turn flow and return stopcocks behind the tank in the kitchen which seems to have isolated the flat from the communal hot water system. The tank is now cold, but I do still have cold water coming out of the hot water taps. Is there anything else that I need to isolate before I drain the radiator pipework? As you have probably gathered I'm a complete novice and don't really understand how communal heating systems work. Would really appreciate any advice.

Thanks

 

[steadyon]

The cold and hot supplies to the taps have nothing to do with the radiators. The central heating (radiator) system in a communal system will normally have water in it at all times.

There may be valves to turn off the supplies to your flat, but they will be on the heating pipes, not on the hot and cold supplies. If you can't find these valves, or there aren't any, or they are stuck, I'd suggest the job can't be done in the way you envisage it. Try asking your neighbours and / or the management company if there are valves, and if so, where they are.

If you do undertake the work yourself:

1. You will have to turn the water off to the heating circuit in your flat (see above for valves).

2. You will have to find a drain off point / valve and drain the water from the heating system. Turn off all the other radiators at both ends before draining. Make a note of the number of quarter turns necessary to close each valve, so that they can be opened the same amount when you refill.

3. Undo the valve connections on the radiator with the faulty valve very slowly. There will be some water comes out, that which is left in the pipes. However. be ready to tighten the connections again if water doesn't stop coming out.

I think you would be well advised to get a heating engineer in who can freeze the pipes going to the affected radiator and can thus change the valve(s) without all the foregoing fuss. I personally wouldn't trust a freezer spray on a communal system - the consequences of failure are too expensive. An electric freezer should be OK.

 

[erichsonb]

Thanks very much for the swift reply. Looking at the pipework I think the valves I have already turned off are for the central heating. I just wasn't expecting these to also stop the heating of the hot water tank in the kitchen, so am just a bit nervous that if I drain the rads, I will also be draining that tank. There is no chance of this is there?

Thanks so much again for the reply.

 

[stani]

Steadyon has given you the best advice in getting a heating engineer who is conversant with district heating systems. There are a lot of proffesional guys on here who wouldn't touch these, let alone a complete novice.
When you have drained your system down how are you going to fill it up again?

 

[thereisawizza]

If this is communal heating I would leave well alone. It could all go smoothly and the system refills ok with no dramas.....

.......Or you could find an isolated cold feed and take out an entire block, end up causing thermal shock to a commercial boiler heat exchanger, upset a neighbours heating (who you just know will be the one who stays up till 5am every morning and owns a pitbull)

Is there a facilities manager etc you could contact? Also is this a private flat in an ex-council block?

 

[PlumbBobBob]

no, more than likely there is a coil in your cylinder through which the heating water flows to heat your hot water. all you have done is stop this flowing which means no hot water until you open the valves again.

 

[erichsonb]

Hmmm. Don't fancy a run in with the neighbours pitbull. Perhaps I need to re-think this then. Yes it's a privately owned ex-council flat. Tried calling the council today but short of getting emergency repair team out, I'll have to wait till Monday - which means no hot showers until then

Thanks for the advice guys.