Protecting a Vacant Property from frost damage over cold months

DoneWorking

The boiler is ten years old

Range: The 2016 version typically has a modulation ratio of up to 1:4 (scaling its power down to match lower heating loads rather than just turning fully on or off).

FreeBear

1:4 modulation range - Not the worlds best. Some of the better Worcester Bosch (and others) will do 1:10.

Mine, a Viessmann 050 will go from ~28kW for CH right down to 3.2kW, but even that low, it will short cycle from time to time even with all the TRVs fully open. Still, even with a 1:4 modulation range, reducing the flow temperature and just running the boiler for a couple of hours (with a thermostat) each day need not use too much energy.

DoneWorking

I think his boiler is a 2016

050-w boiler too.

What's a reasonable option for a wireless thermostat/controller which would work with his boiler

FreeBear

IF the boiler is this one - https://www.freeboilermanuals.com/assets/pdf/viessmann/vit-1.pdf

Then it appears to support OpenTherm. In which case, a Hive Mini V4 might be suitable (get expert advice first). But I dislike anything battery powered. Batteries go flat (usually at the most inconvenient time), some leak and wreck the insides.

Even if the boiler supports OpenTherm, any smart thermostat that has a low voltage relay will work. A dumb thermostat, you need to be a little more careful as some switch at mains voltage - You do NOT one of those. As long as it says "low voltage switching", you should be fine, but again, get expert advice.

Bigphil1474

When we sold my dad's old house, it was empty for 9 months including over winter. We turned off the water to the house and left the heating on 24/7 at the lowest temp of 5c. The insurance required a minimum of 5c. We did a weekly visit to check the house over, turned the water back on for cleaning/kettle etc. then off again, and trickle vents and internal doors all left open. Didn't have any issues and the gas bill was low. This was a mid 90's2 bed semi.

Albermarle

https://forums.moneysavingexpert.com/discussion/comment/82113776#Comment_82113776

From other threads, it seems most insurers insist on a minimum of 15 degrees, although as mentioned in a previous post, this seems a bit OTT. I suppose the insurer is not paying the gas bill ! I would have thought 10 degrees would be a good compromise, as at 5 degrees you could get condensation problems in properties prone to it.