Someone please explain the logic of heating system and thermostat?

sisalka

We have a problem with our new heating system and I could do with some help on this one. Bear with me, its slightly complicated:

After a refurb/extension, half the house downstairs is new and has underfloor heating; the rest of the house is older and is heated with radiators.

We therefore commissioned a sophisticated system that pushes hotter water into the rads at a relatively high 'speed' and less hot at a lower speed over longer time periods into the underfloor. So far so good.

We have thermostats on all the rads. We also have a wall thermostat upstairs on the landing and downstairs in the hall (the rad in the hall has its own thermostatic valve, upstairs landing has no rad).

The main living room/kitchen downstairs has underfloor, no thermostats anywhere. The same in the utility room, adjacent corridor and downstairs bathroom, underfloor, no thermostats. There is, however, a wall thermostat in what we call the bike shed (fewer coils in the floor, thermostat set at 13 degrees, also has the boiler, room meant to be a 'buffer' between cold outside and warm inside). There is a set of manifolds in the utility room, they are all set to the same flow rate. There is a manifold upstairs (for the rads) also all set to the same flow rate.

I am puzzled, how the three thermostats in the hall are supposed to regulate five different rooms upstairs at different temperatures (warm bathroom, cool bedroom, cooler guest rooms, medium warm hall). At the moment the hall is warm, around 20 degrees, all the rooms upstairs are at about 15 degrees. Or am I to leave the thermostat open at say 30 degrees? Would that allow the rads to get enough heat? Or is the thermostat supposed to control the heat going into the manifold? If so, why are all the rads almost always only luke warm, the rooms all equally cold?

With no thermostats downstairs, I cannot understand how the system 'knows' when more or less heat is needed in the rooms with underfloor heating? Can a system work, if the rooms with the underfloor heating has no thermostat in that room at all? If yes, how? And why do we have one thermostat in one of the rooms with underfloor and not in the others?

Logic tells me that something is off but I'm being told by the contractor that I just don't understand the system and that I just have to learn how to tweak it.

We would be happy to pay them to check this for us and explain. The contractors - heating engineers - are telling me I'm wrong (the tweaking again) but my gut tells me that some of this is just bs.

Any insights or suggestions much appreciated. I'm a lay person and it is difficult to talk to someone who has all the jargon and tells me that the thermostats in the hall are building regulations (you have to have one thermostat upstairs - thermostats on rads don't count - and one downstairs - again, thermostats on rads don't count -- that's what we are told anyway).

Help!!

ptogher14

Each zone should have a stat. If you have a manifold system each rad will be plumbed back separately to it. Each room should then have a stat controlling the flow to the rad. The stat controls the rad not the manifold.


Building regs state each zone should have stat. It falls under part L

MicktheMan

OP, tbh, it reads like a right mess.

The first thing I would say is whoever "designed and integrated" the control system(s) is your first port of call to explain how best to use and control the heating.
Controlling both under floor (low temp & slow response) and radiator (high temp and quick response) heat emitters is challenging to get right (both for occupant comfort and efficiency).
But really, having trv's on radiators and also zone wall thermostats in the same space is, in my mind, stupid and illogical (this doesn't mean it doesn't happen). Also, having a zone stat in a space without a heat source is similarly illogical.

So, who designed the control system? Get them to explain it to you.

Neworder79

Most thermostat controls are archaic unusable junk tech stuck in another era.

Heating control should be this easy:

https://nest.com/thermostat/life-with-nest-thermostat/

sisalka

Guys, thanks for the help, that was exactly what I needed. Stats on rads are stats, doubling up on stats on the walls is just nonsense.
Ptogher14 - just read the building regs. I think our installers and electricians got two things mixed up - if you don't have stats on the rads, zones stats are necessary (one or two, depending on the size of the dwelling, that's how we ended up with two). They are not necessary when you have stats on every rad - should be obvious but my guess is that if a lay person and woman to boot asks the questions, the lads simply don't think that she might have a point? I remember how frustrated I was when I opted for not installing the clearly obsolete stats - and everybody told me they were necessary according to building regs. And the so called heating engineers didn't pick that up either? A bit of a muppet show. Just as well that we still have retained money. Part of that is going on getting the system right!
Neworder - that stat looks interesting, thanks for the tip!

Calibos

Are you sure the 'wall stats' aren't just Zone Timer/Controllers and not Thermostats at all?

sydthebeat

Calibos wrote: »

Are you sure the 'wall stats' aren't just Zone Timer/Controllers and not Thermostats at all?

How do these differ Visually from stats?

I've seen plain box type things very similar to stats on walls but with no temp controller, is that them?

sisalka

Ours have temperature grades on them. So I assume they are stats. They also click on and off when I raise the temperature on the display. The Salus operating instructions call them Room Thermostats. So I guess they probably are.

The little stats on the wall in the hall have only temperature on them, no timer or anything, little round things that go from 10 to about 30. Degrees I assume.
Would also be interested what zone controls look like and what they do, how they work.

liveandnetural

post a few pictures

manufan16

It sounds like your downstairs UFH is just one zone and that zone is triggered by the set point temperature stat in the hall, when the temperature drops below the set point your UFH should will come on and will turn off when they reach the set level.

with regards your rad upstairs I would imagine the stats on the rads are controlling the level of heat output to the room and the stats on the wall turn the rads on and off based on set room temperature.