What are the inherent problems of draining down a central heating system

[pesky terrier]

Hello,

Hoping you are willing to give a little general advice to a recently new home owner who has very little knowledge of plumbing, but hopefully enough common sense to seek advice before making daft mistakes.

The property will be vacant for a few weeks this spring. Neighbour is looking in on it and agreed to keep the heating set based on temperatures - to avoid freezing.

For the last three months it cost 425 pounds to keep gas central heating and hot water going during a reasonable mild winter - 3 bed detached, reasonable well insulated, stone built property - and that was the heating being tweaked regularly to account for fluctuating temperatures.

Would a complete drain down of the system be a cheaper alternative going forward - avoiding any possibility of frozen pipes - and what are the implications of draining down in terms of the re-drain and sludge effects. In other words would all the cost and problems associated with draining down be much more than simply keeping the heating on to prevent freezing?

I realize it's coming into spring and less chance of frost so could turn off the system - but depending on what trouble is involved with drain down, I'd rather not take risk turning off completely.

Any useful advice that could help me decide would be most welcome.

 

[southcoastboile]

Personaly I would leave the room stat at 11 degrees. Don't drain it down for a long period of time you will probably regret it imo.

 

[villa_tom]

Just turn your cold mains off if being left vacant. Don't drain the system, leave the stt on low and have the heating come on twice a day for a short while.
If you've got your mains off then if you where to have a burst pipe at least it would stop, and your system won't carry on filling.

 

[pesky terrier]

It was my Neighbour who mentioned the sludge getting around the system, but I was trying to avoid the hefty bills that come with heating an empty house and the possibility of freezing pipes. Thinking it was better safe than sorry. But if I am only going to give myself bigger headaches down the road, then I should avoid the draining I guess.


Cheers

 

[Roger Welton]

If you are really concerned then dose the heating system with some antifreeze, though mains off is a must imho.

 

[pesky terrier]

Thanks Villa,

My Neighbour already turned the mains off in the street, and I think he also emptied the tank in the loft area. I believe he left water in the hot water tank and set it to come on low twice per day. The central heating radiators were each set low and I think the thermostat was on at 15C , timed to come on for a couple of hours a day. So it would seem there is not too much risk of freezing pipes.

 

[Mike Jackson]

A good few years ago I was asked to drain down a heating system in a halfway house whilst new tenants were looked for . The property was four storeys high with around twenty bedrooms and associated rest and living accommodation. I tried to talk the housing association out of it but apparently the insurers were insistent that a vacant property should be drained. It took a good day for two of us to drain the entire system down, hot, cold and CH.

New tenants were found more quickly than expected so we were asked to go back in and recommission. Fortunately when the heating system was refilled I didn't put any inhibitor in on the first fill as 8 radiators pinholed. As if that wasn't expense enough the CH pump had also seized. This was a good ten years ago and the replacement pump cost nearly a thousand pound then, it was a monster and took two of us to change.

As well as the damage to the heating system, the water damage from the leaks there was now also condensation staining from where the property had been left cold throughout the winter months. If the system had been left kicking over and someone paid to check once a week it would have saved a fortune.