Winter holiday - what to do with heating and hw

[tomo51]

I'm going to be away 4 weeks over Xmas and considering what to do with our heating and HW in order to minimise cost but not introduce risk of damage to system through frozen pipes etc.

We have a bit of an unusual setup for our house, think its maybe referred to as a system boiler or thermal store? We have an old ideal standard classic boiler that heats up water in the cylinder to 70c. The HW is always ON so the temp of the cylinder is always maintained at 70c. The hot water stored in the cylinder is then used for the radiator circuit, with a nest thermostat triggering a heating pump when required. We get HW through mains cold passing through a coil in the cylinder, so we get HW at mains pressure.

I was planning on setting thermostat on Nest to 4c, and then raise it to 15 daily to run the pump and circulate the HW around the rad circuit. To keep a bit of heat in the rad circuit and stop the pump from seizing.

I'm unsure what to do with the HW schedule, and the cylinder temp. Was considering setting the HW to run for an hour daily, to heat the HW back up to temp, then set the CH to run at the same time. But I'm thinking it probably doesnt need to be set to 75c, and wondering what the minimum it would temp that would be recommended for the HW in the cylinder? The temp on the cylinder is the control that kicks the boiler in.

We live in the UK near Hull so not in a massively cold area. The other option would be to just turn it all off and then set the schedule to kick in as usual a day or so before we get back. But would this risk the pipes freezing internally? I suppose its all dependent on the weather! We have 8mm microbore to the rads which run off a bigger flow and return pipe.

Would appreciate any thoughts and or suggestions anyone has.

 

[RandomGrinch]

I suppose its all dependent on the weather

...well that's one of the benefits of having the Nest!
You always have the ability to log-in remotely, monitor the temperature, adjust the schedule and turn the heating on/off as required

 

[tomo51]

Indeed ... That is a good feature of Nest. As long as the WiFi stays up and the thermostat stays connected to the boiler control etc

I'm kind of looking for a set and forget type solution though, so I don't have to keep monitoring it.

Also, the nest doesn't allow me to control the HW cylinder temp. This is a physical thermostat on the cylinder. Interested to hear what the minimum temp I could get away setting this at. Don't want to keep it at 70c really whilst away, even if boiler is only heating it up to that once a day.

Ideally, I'd like to set this to the minimum to prevent freezing risk, and I'll then ask someone to come in a couple of days before we're home crank it back up to 70c so the house isn't an igloo for when we get back at 11pm in January!

 

[JohnD]

Your insurers will probably say heating at 12C or they won't cover bursts. If you are in England this will cost very little because the daytime temperature is seldom that cold.

If you have pipes and tanks in the loft, turn off the water and run the tap to drain the tank. With no water being used, the static water in the pipes will eventually get very cold, and can freeze on a frosty night. Well insulated lofts get very cold. As you are not in the house there will be no flow of warmer water.

I had a loft burst a few years back.

 

[ianmcd]

the nest doesn't allow me to control the HW cylinder temp

you dont have a HW cylinder, you have a thermal store, absolutely not the same thing