thermostat & temperature control issues

[nereo]

We're living (renting) an old, draft New England home, and since its gotten cold we've noticed that the thermostat is neither accurate nor precise. If we set it to 64ºF it basically kicks on until the house is sweltering.  If we set it to 58ºF it won't kick on until the house is near freezing.  Heat is via hot-water radiators powered by heating oil.

The furnace itself is new (installed in 2016).  Landlord is overseas but in email conversations he said the heating has never been precise, and they just 'lived with it' by treating the heat like an on/off switch (they turned it on for an hour or so in the morning, then again in the evening, but otherwise left it off).  Not as practical for us given our work schedules. The existing thermostat is a 1970's style dial (no programmable).

Anyway - he gave me the go-ahead to replace the thermostat and deduct the cost from my rent, and/or I can contact the company that installed the furnace and ask them to check it (they apparently did so last spring and said it was functioning normally).
Questions
1) does this sound like an issue that can be resolved with a ~$50 thermostat from HD (a basic programmable one)?
2) is the temperature sensor which controls the heat built into the thermostat itself, or would it be located someplace else?

[YttriumNitrate]

1) does this sound like an issue that can be resolved with a ~$50 thermostat from HD (a basic programmable one)?
2) is the temperature sensor which controls the heat built into the thermostat itself, or would it be located someplace else?

1) Swapping out the thermostat might fix the problem. Even if you weren't having issues with heating, swapping out a 45 year old thermostat would still be a good idea.
2) I'm sure some fancy wifi ones have multiple sensors, but for a standard thermostat the temperature sensor is going to be in the thermostat itself.

[neo von retorch]

Modern thermostats have a setting for how far past a temperature they run. On the other end, the boiler likely has two settings - minimum water temperature and maximum. If it's a really wide range, it'll run the boiler for a long time in between, but if it's a small range, it'll kick on and off way too often. That wouldn't explain the water running through the pipes though - that's controlled by the thermostat and the zone valves.

One thing I do find with the old mercury thermostats is that when they are wearing out, sometimes they don't "tilt" in line with the temperature, and the electricity can be conducted through them when it shouldn't be. I do think the $50 Honeywell 7-day programmable thermostat is the best bang for the buck. Though if you have a consistent enough schedule, the 5-2 will work well enough for you.

[nereo]

thanks for the responses.
I think i'll drop the $50 (heck, it's not even my money) and replace the thermostat and see if that solves the problem - seems like it might.
 If nothing else we'll be able to program the thermostat so we don't have to manually adjust it multiple times every day.
cheers

[HipGnosis]

If you won't be there long, I would buy the programmable thermostat and then take it with you when you move.
Take pics of the wiring of the old one before/as you take it off so you can put it back.

[Sibley]

My parents have steam radiators, and they can't use programmable thermostats because the cycling time isn't suitable for the boiler. Or something. [insert more detailed explanation that boils down to, they say it works, and for some boilers it's ok, but not for their boiler] Rather than risk damaging their very old boilers by cycling them too often, they got a modern, non-programmable but electronic thermostat. No more dial! The temp will range about +/- 5 degrees, just because that's part of the deal with how their boilers were designed to operate.

[MDM]

Questions
1) does this sound like an issue that can be resolved with a ~$50 thermostat from HD (a basic programmable one)?
2) is the temperature sensor which controls the heat built into the thermostat itself, or would it be located someplace else?

1) Hard to say with the data given.  Is there a temperature setting between 58 and 64 that results in some reasonable heating cycle?
2) Usually in the thermostat itself.  For hot water heat, often the thermostat in the house will cause a hot water pump to kick on, while the furnace will go on when both
a) a hot water pump is on, and
b) the water temperature exiting the furnace is below some setpoint.
Is that how your system works?

[nereo]

Questions
1) does this sound like an issue that can be resolved with a ~$50 thermostat from HD (a basic programmable one)?
2) is the temperature sensor which controls the heat built into the thermostat itself, or would it be located someplace else?

1) Hard to say with the data given.  Is there a temperature setting between 58 and 64 that results in some reasonable heating cycle?
2) Usually in the thermostat itself.  For hot water heat, often the thermostat in the house will cause a hot water pump to kick on, while the furnace will go on when both
a) a hot water pump is on, and
b) the water temperature exiting the furnace is below some setpoint.
Is that how your system works?

Yes, that is how our system seems to work. Travel prevented me from addressing the thermostat/temperature issue this weekend, but hope to get to it this week.

As the landlord has agreed to cover the cost I'll be leaving whatever I get here.  Photos of the wiring is a good idea, should I need to default back to the original for some reason.

[J Boogie]

This could also be a great opportunity to have some thermostatic radiator valves put in.

These can be installed pretty easily on each radiator to limit the opening and therefore the heat output.

This way you could leave it at 64 and tighten up each valve until it's at a comfortable (and affordable) setting, rather than having the all or nothing problem.

Your landlord sounds pretty cool. You could email them this idea along with some basic info about its benefits and a quote from a local plumbing/heating company for install.

[AccidentalMiser]

Yes, I would replace the thermostat.  Yes, I think a basic programmable would work but there a lot of variables.  How many wires go to your current thermostat and what color are they?