Is there such a thing as a thermostat limiter?

OP do they just not realise? Perhaps you could mark the optimal/max temperature on it with a sharpie?

You've said they go out to communal areas all day. Could you set the timer on the boiler so that it goes off in the morning until later on the day?

We have a Drayton+ digital thermostat and (according to the instructions) you can set a maximum and minimum temperature. We've never used it (or rather it is set at 30C so is beyond anything we would exceed) so I can't say for sure how effective it is, but it is there as a function.

By the way, I have an Emerson Sensi and it looks like a traditional thermostat, so may be more appealing/less scary for your parents. I am in the USA, but pretty sure it's available in the UK (and significantly cheaper than all the fancy trendy ones)

Just replace the thermostat with a smart thermostat (assuming they have wifi...if not, it's a little more complicated). I attached a smart thermostat to my ancient heating system and can now check if I left on the heat by accident from anywhere in the world (extra useful during the last 2 years...NOT).

We have a Tado heating system which I’m sure will be similar to Hive. It does need wifi and there is a cost to buying the valves and system in the first place. But our heating can be programmed and controlled via an app on our phones; there is a setting where we are prompted to turn off the heating if we leave the house; you can set child locks to prevent the valves being turned up manually, and each radiator can be controlled individually on the app so unused rooms aren’t being heated unnecessarily. Would that be a possibility? You might have to persuade them to have wifi put in but it sounds like it would be worth it if it would stop them roasting themselves day and night!

We put my Mil's heating on 24/7 once we found she got up in the night.

We put my Mil's heating on 24/7 once we found she got up in the night.

Wow 30 is excessive. If you can't get WiFi and hive, do they at least have a programmable thermostat so that you can programme it to be off when they are out? My quite old fashioned one now has 4 settings a day and 7 different day programmes - so it could be different on weekdays and weekend....or even different from day to day. E.g. you are at day centre Tuesday so heating goes off 30 mins before you leave and comes on 30 mins before you return.....
That type of thermostat is about £100 to buy, and then needs something added to the boiler to make it work.

No judgement here, as we have no idea of the full story.

Sorry OP. My frail elderly parents are terrified of increased heating bills, and are not warm enough. They are hundreds of miles away and whenever I talk to them insist they are fine, and wearing lots of clothes. They are also poor, proud, private and won't accept anything from me. I've pleaded with them to let me pick up their heating bill but they won't hear of it.

I'm worrying about this all the time currently.

But if they feel cold they should be able to have the heating on whatever temperature they wish , ejderky people are less mobile, not generating self heat

Their home could be drafty etc.

I find the whole concept of you deciding what temperature they have their home at frankly awful

30 is tropical temperature. I would just wilt in that.

I know many elderly people do feel the cold more. My mother does. Her house thermostat is set at 20 though, and in the winter that means her heating is on a lot, but most of her house (a small bungalow) is bearable. If she wants extra heat during the day or in the evening she has a gas fired log burner in her lounge which she has a remote control for and that gives her the boost she needs without turning the rest of the house into a furnace.

I'm convinced that she has also tried to cook me with the burner, when she forgets that she has put it on. 😯😠😂

30 is very high! Plus in the current set up then they may well literally bankrupt themselves.

Erm... Age UK recommends 21 degrees as the right room temperature for elderly people, with 18 degrees in bedrooms at night, and MIL's GP said her heating should be no higher than 25 degrees (she's 90+ and housebound).

Why Are Elderly Always Cold - Do Seniors Feel Colder as They Age? - RespectCareGivers
i would not bring it down too much or too fast. start with 28 and aim for 25C

Surely that can’t be healthy? Even hospitals and care homes don’t put the heating that high.

the elderly and their own body thermoregulation IS NOT the same as 40-50-or even 70 year olds.
having the house at 25-28 is not at all unusual nor is 30C.
it would be cruel for an elder to be in such cold temps as most are accustomed to (generally 18-21C).
warming blankets can lead to skin burns and is not a suitable solution either.
best option is to only heat certain rooms and keep some rooms shut and cooler.

Holy smokes for that temp, I'm usually 18-20 then have a dressing gown on, if needed.

Excellent idea. Definitely get those.

My mum has a thermostat on her boiler which she knows nothing about! We turned that down and I reckon it saved money. What phone contract are they on? Now broadband is doing an offer at the moment for broadband 65mgbs, landlines and anytime call, £23. Can you sell the deal and get them to change providers! Life is so much easier when you can access the Internet at their house.
Do they have any impaired capacity. Get yourself PoA.

30?! Fucking hell, I would absolutely wither and die. Like you said, they are going to be bankrupt unless they have very significant savings.

Do they have WiFi? You could get a WiFi enabled thermostat and control it remotely. There's always an old fashioned clear lock box to keep them away from it.

30 degrees, Christ, I see what you mean!!

If you turn down the temperature on the boiler itself to 50 degrees, this saves energy. The house will reach the same temperature (so still 30 degrees I'm afraid!) but will take longer to warm up.

Heated throws? Then they might turn it down themselves