In alt.home.repair, on Tue, 23 Feb 2021 14:26:28 -0500, Tekkie©
wrote:


On Sat, 20 Feb 2021 03:05:37 -0800 (PST), Alexandre Verri posted for all of us
to digest...


I bought a house in Ireland two years ago and I still have some doubts about how the heating system controls should work.

My house has one thermostat and also a programmable mechanical timer. This is what I refer here as the control system. The actual behaviour of the control system is:

Regardless of the programmed timer, if the room temperature is less than the temperature set on the thermostat, the boiler and pump start working to heat the house.

If the room's temperature is bigger than the temperature set on thermostat and the timer fires, the boiler and pump start working to heat the house.

It seems a strange behaviour, this is not what I would have designed. I would prefer the following:

If the room's temperature is less than the thermostat and the timer fires, the pump and boiler should start working.

It's conceivable that they put the parts together wrong Conceivable,
but very unlikely. It coudl be that the timer should control the pump
and boiler like you want, though I'm not sure what would happen when
tthe timer is ... off, is that the other setting? Would the house get
really cold if the timer were off and that stopped the boiler from
working. Or does the timer somehow change the temp setting like one of
the ansers though could be the case.

Be absolutely sure you have a totally understandable drawing of how it
is connected now so you can put it back that way when you realize you've
made it worse. But maybe you'll make it better.

Don't depend on your memory. It's amazing how easy these things are to
forget in only a few minutes.

Take photographs and make functional drawings and schematic drawings and
then stare at the schematic until you understand how it is set up, what
the timer is supposed to do (and how it's supposed to do it) (It seems
pretty clear what the other parts, the thermostat, pump, and boiler are
supposed to do.) And when you know what the timer does and what it's
role is supposed to be, then you'll know if you can rearrange things or
not

What about other houses on the street? Or anywhere in town? Do they
have the same setup? This is a good way to meet your neighbors. If uou
ask to see his furnace, he might turn out to a pro or a long-time owner
who can tell you what's wrong.


I had a room air conditioner and when the thermostat said was cool
enough it stopped the compressor, but the fan ran constantly. If it
cooled off 30 minutes after I went to bed, the compressor would stop but
the fan would run all night. I hated that. I hated the noise. All the
connections were slide-clips and I only had to rearrange 3 of them so
that when the thermostat said it was cold enough, the fan and the
compressor stopped.

The designers don't like this because there is no fan to circulate the
air so that the thermostat knows almost immediately when the air is too
hot. But I don't care if it has to wait 30 or 60 minutes to find out.

Is it possible the timer was added by a previous owner, not by someone
skilled in heating? That would make the chance of it being wired
incorrectly a lot higher.

Please share your thoughts on this, how is your control system?