So, new house, it has TRV's which I've never had before. I used to
have non-TRV and fitted a prog thermostat which worked well, and since
I was renting, I reinstated the old one and took the prog with me.

However, I'm a bit unsure as to where to site it (there's currently no
roomstat at all on this setup, bypass rad is the bathroom upstairs).

I know if you put it in the same room/too close to a TRV the whole
thing goes a bit wibbly, but I'm sort of limited in placement here.
Ideally closeish to the boiler to avoid huge runs of cable woudl be
good.

Is doing this going to run foul of the Part P regs?

Boiler is in utility room off kitchen (there's a door between kitchen
and utility room, no water in utility except plumbed-in washing
machine). Boiler is a combi, and apparently can have a roomstat fitted
(currently just has 24/hour timer integrated with boiler).

Kitchen goes through to livingroom - working fireplace in there, along
with TRV rad. Kitchen's clearly not ideal, due to heat fluctuations
whilst cooking. Livingroom seems similar due to fireplace (not used
every day, but if it is, can see it stopping heat to rest of house cos
the stat will be off). Hallway/stairs is miniscule, and again, big
temp shifts as door opened/shut. Upstairs landing might be feasible,
but works out quite a way from the boiler. Bathroom's above the
utility room... and the rest are bedrooms.

I'm half-minded to put it in the side hall (off kitchen, door to
external, not d/glazed, no rad, off that is downstairs WC, no rad
(though may add one in future) - but the door to the kitchen is left
open to get heat to that area, in absence of rad.

Basically, just how close to a TRV rad would a roomstat have to be to
completely bugger it all up? are we talking right next to it,
opposite, far side of a 12'x12' room?

Any help appreciated greatly - 24 hour timer is pants and I can see
it's going to waste loads of gas (and thus money) that I can ill
afford.

Velvet

I know if you put it in the same room/too close to a TRV the whole
thing goes a bit wibbly, but I'm sort of limited in placement here.
Ideally closeish to the boiler to avoid huge runs of cable woudl be
good.

Or you can use an RF one.

Is doing this going to run foul of the Part P regs?

Probably not. I'm not quite sure.

Kitchen goes through to livingroom - working fireplace in there, along
with TRV rad. Kitchen's clearly not ideal, due to heat fluctuations
whilst cooking. Livingroom seems similar due to fireplace (not used
every day, but if it is, can see it stopping heat to rest of house cos
the stat will be off).

I prefer to use the living room, as it means that this room is the most
accurately controlled. However, this should not be done if this room has
auxilliary heating (i.e. your fireplace). Also, you may need to artificially
throttle back this room a little when balancing, so it is the last room to
heat up.

Basically, just how close to a TRV rad would a roomstat have to be to
completely bugger it all up? are we talking right next to it,
opposite, far side of a 12'x12' room?

It could be totally adjacent. You just replace the TRV with a lockshield, or
just turn the TRV to max, which has the same approximate effect.

Generally hallways are chosen when the living room has an additional heat
appliance. In my case, I'm subzoned. The living room prog stat affects the
front room and hallway as well. I have a bedroom zone and a kitchen zone. I
will have a loft conversion zone and a conservatory zone in the future.

Christian.

I didn't want to remove another TRV and replace with lockshield, to be
honest, because I already have a bypass in the bathroom - though i
suppose it wouldn't necessarily affect that, and would just act as a
bigger bypass (add them together)?

Maybe the solution is to fit the extra rad in the downstairs WC -
though not planning doing that till spring, on account of it being a
DIY, me never having DIY'd plumbing before, and the entire system being
drained down to do that, sort out a TRV on the wrong side of a rad -
noisy; and I have a combi, so no HW while the system's drained down,
which could be for several days depending how I get on with learning
while I go!

I could then put the stat in the hallway adjacent to it. The door to
outside isn't opened all that often, compared to the front or back
door. And it'd make it a lot more convenient for the wiring - it's a
matter of drilling a hole through two internal walls and running it in
surface mounted trunking (unplastered brick walls).

Am I right in thinking that if I opened a TRV to max, it wouldn't
switch off - and that I could balance the system by the lockshield on
it, and it would then be acting as a non-TRV rad? I'm thinking that
might be an easier way to go about this, in the event I decide to
revert to non-progstat operation if it doesn't work out - I could just
disable the stat, and re-balance and bring the TRV back into operation
again?

Velvet wrote:
I didn't want to remove another TRV and replace with lockshield, to be
honest, because I already have a bypass in the bathroom - though i
suppose it wouldn't necessarily affect that, and would just act as a
bigger bypass (add them together)?

Maybe the solution is to fit the extra rad in the downstairs WC -
though not planning doing that till spring, on account of it being a
DIY, me never having DIY'd plumbing before, and the entire system being
drained down to do that, sort out a TRV on the wrong side of a rad -
noisy; and I have a combi, so no HW while the system's drained down,
which could be for several days depending how I get on with learning
while I go!

I could then put the stat in the hallway adjacent to it. The door to
outside isn't opened all that often, compared to the front or back
door. And it'd make it a lot more convenient for the wiring - it's a
matter of drilling a hole through two internal walls and running it in
surface mounted trunking (unplastered brick walls).

Am I right in thinking that if I opened a TRV to max, it wouldn't
switch off - and that I could balance the system by the lockshield on
it, and it would then be acting as a non-TRV rad? I'm thinking that
might be an easier way to go about this, in the event I decide to
revert to non-progstat operation if it doesn't work out - I could just
disable the stat, and re-balance and bring the TRV back into operation
again?

You could remove the head from the TRV so that nobody turns the rad off
by accident - will ensure that it stays on constantly too.

Am I right in thinking that if I opened a TRV to max, it wouldn't
switch off

Basically, yes. It will switch off about 30C. That would only happen if your
programmable thermostat is broken.

Christian.

S'only me, and i'm not likely to turn it off :-) Last place, had
normal valves on both ends of hte rad, no lockshields. I balanced it
all, 13 years later still hadn't been fiddled with :-)

Aaaah, the joy of not having fiddling kids :-)

That might be a good interim solution to it if I do put the heaterstat
in that hall and the kitchen TRV interferes (thus saving me draining
the system down, and leaving adding the wc rad till spring) - sinc ethe
kitchen TRV is the one on the wrong way roudn that shudders as it
closes... keeping it on full would solve that problem, though obviously
I'd still have to manually compensate for cooking affecting the
operation of the roomstat, being in the hall should see it being far
enough away to nto be too badly affected.

I think I see light at the end of the tunnel, and a way to fit the
roomstat and leave me being able to easily revert to the
pre-installedstat setup if it does cock it all up :-)

Cheers, UK-DIY, ever useful!