Central heating controls in empty house over winter

gterr

Hi there,

I have a holiday cottage which will be empty for part of the winter. I will be able to inspect regularly, but I want to keep some heating on to keep the place aired and to avoid burst pipes etc.

The cottage has a wet radiator system powered by an electric boiler on Economy 10, radiator valve thermostats plus a room stat in the hall. The hot water cylinder has a cylinder stat.

My idea is to have the heating and hot water come on for three 45 min periods per 24 hours (during the 3 off-peak times), set the rad valves at 1 or 2 and the room stat at 15 C. Is this reasonable, or too wasteful?

suki1964

Last year when it was minus 15 and lower most nights for 3 weeks, I found out that 6 hours was too long to keep the boiler off - it froze

SYNERGY

There is another way, but it is a little involved.

The central heating system can be protected down to -25 with the addition of the correct quantity of antifreeze.

All the main manufacturers of central heating corrosion inhibitors also produce compatible antifreeze with a life span of 5 years or more on average.

The domestic hot water boiler would need to be drained, the domestic hot water pipe work would need to be drained.

The cold water pipework would need to be drained, all presuming a drain tap ( wouldn't let me post the correct term ) has been fitted at the lowest points and is easily accessible.

With the cold water turned off at the stopcock the toilet should be flushed to empty the cistern.

To prevent the toilet bowl cracking, car antifreeze ( propylene glycol biodegradable ) can be added, likewise to such as bath, sink, shower etc. traps.

Seems a bit long winded, but once the central heating system has antifreeze in, the other bits don't take long.

This is how it is done in summer cottages in Sweden etc.

Pincher

The main issue with not draining is power outage, which is more likely in remote locations. It's not just power cuts, the RCD can trip because a rodent chews through a cable.

If you can inspect often, then I would just leave the timer ON during Economy 10 hours, and keep the central heating thermostat on low, like 10 degrees or less. The TRVs should be on five.

Draining the system has its own issues. The empty pipes now have oxygen and moisture, promoting rust. The antifreeze sounds good. Don't forget the loft tank when dosing.

Tubular heaters with frost stat can provide extra backup. They are particularly good for the loft tanks, which are outside the insulated area. Well, unless it's been done professionally, where the correct approach is to have no loft insulation under the tank, but cover it with lots of lagging, so the tank benefits from rising heat.

gterr

Thanks for all your comments. Some good ideas there.

I don't really want to drain down the system because I may get the odd booking - at short notice - for the cottage, so need to be able to get it up and running again quickly. I could switch off the cold water at the stopcock though.

Just a quick question for Pincher: why would you have the TRVs on 5 rather than, say, 1 or 2? The lower numbers should still have the radiators getting warm whren the room temp is below about 17 C.

Many thanks.

Pincher

When you want to warm the house up, you want to do so quickly, and then the thermostat cuts out, job done. If you set the TRVs too low, the thermostat does not cut off the heater, so it's heating away, but your TRVs have shut off already so it's just wasting energy.

If there is no bypass radiator, the heater will shut off automatically on overheat, but only if the overheat thermister is working. It's like the automatic bypass valve in a gas boiler, it's a great backup, but you shouldn't be using it all the time.

a&akay

gterr wrote: »

Hi there,

I have a holiday cottage which will be empty for part of the winter. I will be able to inspect regularly, but I want to keep some heating on to keep the place aired and to avoid burst pipes etc.

The cottage has a wet radiator system powered by an electric boiler on Economy 10, radiator valve thermostats plus a room stat in the hall. The hot water cylinder has a cylinder stat.

My idea is to have the heating and hot water come on for three 45 min periods per 24 hours (during the 3 off-peak times), set the rad valves at 1 or 2 and the room stat at 15 C. Is this reasonable, or too wasteful?

If it was me I'd set all C/H timers on 24/7 and the hall thermostat on 10 degrees. Leave all doors open. I doesn't matter what yout trvs are currently set at now, leave them as they are, the hall thermostat will control the heating. One issue may be anything in the loft? I know someone who did the above last Winter after their parents died. The loft pipes froze and dumped mega amounts of water downstairs. No insurance as the house was technically unoccupied. I'd leave the loft hatch open and construct a tunnel of polystyrene foam or rockwool on temporary supports to all susceptible frost areas if so.

gterr

Thanks for the ideas. I do have a frost-watcher heater in the loft, and I will leave the loft hatch open and doors open elsewhere.

Still can't decide whether to have three bursts of heat per 24h with room stat at 15C, or CH on all 24h with lower setting on the stat. (Electricity bill is an issue, too!)

I did have a burst pipe in the loft last winter when we were in the middle of installing the new CH system and consequently had no heating on. £8,000 damage, but thankfully we were covered by insurance. DEFINITELY don't want a repeat of that!

Pincher

Just thinking out loud.

Thermostat calls you via telephone line when it's cold.
Alarm systems can call via telephone line when triggered. The sensors work by contact relays, which is how a thermostat works.

Home automation. You can check on the temperature of the house through the internet from an applet or browser, and turn on the heating remotely. Easy to do with broadband, but old timers used to do it with dial-up modem connected to a BBC micro.

Also, your "electric boiler" may have frost protection that comes on automatically any way.

Swipe

Due to the last couple of winters everyone expects there to be prolonged extreme cold again this winter. Chances are, this will be very unlikely. I'd be more inclined to keep a close eye on the short range forecasts and deal with any cold spells accordingly rather than leave the heating roaring away with overnight lows of 7C.

uptomyeyeballs

There doesn't look to be any real cold weather in the rest of November, and it could end up being one of the warmest Novembers on record. December weather is a long way off yet, but the chances of getting two consecutive severe Decembers are very remote. More likely the coldest weather this winter will be late January and February.