Can I use hot water with central heating system drained?

paperclap

Hi all,

I’m soon looking to drain my entire central heating system, in order to remove the radiators, decorate behind them and replace them.

We’ve an old Potterton Profile 40E conventional boiler (cold water tank in the loft and hot water cylinder in the airing cupboard).

We’ve an old Potterton programmer too, where the central heating and hot water can be turned on independently.

Once the radiators are off, I would imagine prepping and decorating the walls behind will take a good few days… so, you guessed it, it would be good to have the hot water on during that time.

What may also throw a spanner in the mix, is that we’ve a towel rail radiator in our bathroom, which seems to be connected to both the central heating and hot water systems (in that it gets hot if either are turned on). Note though, this radiator won’t be coming off the wall at all.

Is it possible to turn on the hot water with the central heating system entirely drained? And, will I need to isolate the bathroom radiator in any way?

Thank you in advance.

Jeepers_Creepers

The water in your radiator system - the 'system water' - is the same as wot's heating your hot cylinder (via a coil of copper tubing inside the cylinder). So, if you drain your rads, you'll have no water in your boiler to circulate round to heat your cylinder either.

You'd really need to cap off the flow as it heads for the rads, and also the return as it comes back from them. Capping the flow to the rads should be relatively easy as you'd do it at the CH valve. Capping the return will likely need cutting the pipe to insert the cap.

Jeepers_Creepers

Obvious solution - use the immersion heater.

Le_Kirk

Do you have an isolation valve at each end of the radiator?  If so, just isolate one rad at a time, drain the rad, take it off, prep and decorate before replacing it and refilling it with system water.  When finished you will need to top up your inhibitor as it will be diluted.

Jeepers_Creepers

D'oh! Of course! Just isolate every rad and remove them all. Leave the system pipes full of water, and ensure the CH side is turned off fully. The towel rail will act as a by-pass should it still be needed.

(Watch out for TRVs letting by - they are very prone to doing so...:-(  )

Laurence, don't forget to add inhibitor on refilling. And run a hose through each rad to flush them out while you are at it.

FreeBear

Le_Kirk said: Do you have an isolation valve at each end of the radiator?  If so, just isolate one rad at a time, drain the rad, take it off, prep and decorate before replacing it and refilling it with system water.

When you close of the valve (lockshield) put a mark on the stem & body and count the number of turns needed to close it. Make a note of it somewhere safe... After refitting the radiator, open up the lockshield the same number of turns, lining up the mark (you did use an indelible marker pen...).

If you don't count the turns, the system will need to be balanced again which is not always an easy thing to do..

Rosa_Damascena

Having read this thread I think I'll leave it to the experts.

twopenny

Got to say I agree if it's going to take some time.

Taking one at a time would be the most sensible thing to do if you want to maintain your daily life while doing so.

Just get all your necessary equipment in a box to use each time.

Jeepers_Creepers

It doesn't make any difference (unless you actually need the warmth) whether you remove them one at a time or all in one go