TRVs and room thermostats/temperatures

r3nu4l

I have very little plumbing knowledge...as will become evident by the following question

If I turn my TRVs in some of the rooms in my house down to a setting of '2', does this mean that my heating system will then forward some of the hot water to other radiators that normally take an age to heat?

I have quite a few radiators in my house but the one in my office struggles to heat properly, even when the TRV is set to '5' and the heating has been on for a few hours. It never heats to full capacity. The oil boiler temp is currently set at 68C.

I do have a Sauter 210 remote thermostat but I don't want to bring that into the office during the day and have the rest of the rooms piping hot while the heating struggles to heat my rad to a sufficient temp. EDIT: I've not been using the thermostat at all since I moved into this house but equally, want to know about how this works along with TRVs...

Any advice appreciated.

Irish Steve

The TRV will only close when the room gets to the temperature that's been selected for the room, but there are other factors that will come into play.

If you're new to this house, and don't have a long knowledge of the performance of the system, it may just be a case of doing an exercise to balance the system, where the valve at the other end of the radiator from the TRV is partially (almost completely in some cases) closed to restrict the water flow through the radiator, and ensure that the other rads are getting their fair share of the total available heat.

It will be worth taking the thermostatic head section of the TRV off, and making sure that the small pin in the centre of the valve stem is free to move in and out, these can and do sometimes stick, and if the valve is closed to a low or off setting for a while, when it's re opened, they can stick in the closed position, even though the head is "open". Press the pin in with something metallic, or even the head of the TRV spindle, and if it doesn't move in and out freely by about 5mm, gently help it with a pair of pliers, and once it's moving, operate it a few times until it moves freely before replacing the head unit.

To see if there are balancing issues, close the TRV's on all but one radiator, set that one to full open, and see if it gets really hot, then close that TRV and move to the next, especially the office one that you mentioned seems to be struggling. If the office rad gets up to temperature with the others closed down, then the others need to be balanced to reduce their flow a bit and allow the flow to get to the office. it will be a case of changing a few, and seeing if it makes a difference, and you will have to go at this several times before you get it right.

On most radiators, the check valve is normally about right at between one and 2 and a half turns open from fully closed, more than that and you may be into a power flush, or getting the pump performance checked out, and if the rad is very close to the boiler and small, then even less than one turn open may be enough to heat the rad adequately. When doing this, the TRV at the other end needs to be fully open to allow maximum flow through the valve, and then reset to "normal" when you finish the rad.

The other possibility is that the system may be partially clogged up and need a power flush to clean out a build up of corrosion and related muck that can in the worst case completely block the flow through one or more radiators, but you've some detective work to do before making that determination, and if you have to get the system power flushed, there are a number of people here who will be able to advise you in more detail than I have, and they have the specialist (expensive) equipment that's needed to do that job properly.

In respect to the boiler stat setting, It might be worth raising it a little, and aiming for about 75C, but if the system is being used to heat hot water as well, if the hot water is not monitored by a thermostat on the tank, that might be a little too high. Ideally, hot water needs to be stored at 60, so 68 is not giving much of a differential on the input temperature, but tread carefully on this one, especially if you have younger children who might be at risk of scalding from unregulated hot water, which might be the case depending on the age of the system.

r3nu4l

Very comprehensive answer Irish Steve! Thank you. A lot to think about and do there but I'll give it a go. Yeah, the boiler heats the water too and there are small kids in the house so I'd better leave the boiler temp as is. However, I can try the balancing test first and see how that goes. If I could thank your post ten times I would

Dtp1979

r3nu4l wrote: »

Very comprehensive answer Irish Steve! Thank you. A lot to think about and do there but I'll give it a go. Yeah, the boiler heats the water too and there are small kids in the house so I'd better leave the boiler temp as is. However, I can try the balancing test first and see how that goes. If I could thank your post ten times I would

Once your water is set to 60 you coujd always fit a mixing valve in the Hotpress. This way you can adjust the temp coming out of your taps to a comfortable 38-42 or whatever you desire.
If you bleed some water from a radiator is it discoloured and black?

cerastes

Are there any tank stats that allow for variable programming of the time and temperature?
Really 60 seems a lot to heat a tank to all the time, for the purpose of legionella, wouldn't it only need to be heated to 60 about once a week?
If this could be programmed automatically to do weekly regardless of any other demand.

Dtp1979

cerastes wrote: »

Are there any tank stats that allow for variable programming of the time and temperature?
Really 60 seems a lot to heat a tank to all the time, for the purpose of legionella, wouldn't it only need to be heated to 60 about once a week?
If this could be programmed automatically to do weekly regardless of any other demand.

Probably be handier to put a seven day timer on your immersion and set it to come on once a week with the temp set to 65.
Time it so it comes on after the oil/gas has already been heating the cylinder as this will give the immersion very little work to do.

cerastes

Dtp1979 wrote: »

Probably be handier to put a seven day timer on your immersion and set it to come on once a week with the temp set to 65.
Time it so it comes on after the oil/gas has already been heating the cylinder as this will give the immersion very little work to do.

Would this be in a separate circuit? Parallel to the normal use one? Otherwise how would you heat for normal usage to around 40 degrees all the rest of the week?

I was thinking of a programmable tank stat that could be set in one go, just like a programmable room stat

Dtp1979

cerastes wrote: »

Would this be in a separate circuit? Parallel to the normal use one? Otherwise how would you heat for normal usage to around 40 degrees all the rest of the week?

I was thinking of a programmable tank stat that could be set in one go, just like a programmable room stat

You could leave the oil stat at 40 all the time and the immersion would boost it up once a week. Probably safer to do it twice a week or every 4 days

cerastes

Dtp1979 wrote: »

You could leave the oil stat at 40 all the time and the immersion would boost it up once a week. Probably safer to do it twice a week or every 4 days

Its not oil, gas sealed system, there isn't a temp on the boiler controls, no immersion.

r3nu4l

Dtp1979 wrote: »

If you bleed some water from a radiator is it discoloured and black?

No, water is clear from all rads on bleeding.

As for the rest of the thread...I'm lost!

I'll stick with trying out a few things Irish Steve mentioned then think about timers for the immersion and all that Thanks everyone, as Arnie says...'I'll be back'!

freddyuk

1. You need a cylinder stat if you don't have one and set to 55c 2/3 of the way down the cylinder.
2. Set the boiler to 75c - 80c
3. Open all the TRV'S fully and close all the other "lockshield" valves on the rad's except the furthest one which is giving low heat. Open the furthest rad valves fully. Turn on the boiler/heating and see if this radiator heat up as it should within 5 minutes.

Then report back here the result.

Of course when you bleed a rad it will give you clear water as all the black sludge is at the bottom!
Forget about "boiling" the cylinder every 4 days it is not required.

Dtp1979

freddyuk wrote: »

1. You need a cylinder stat if you don't have one and set to 55c 2/3 of the way down the cylinder.
2. Set the boiler to 75c - 80c
3. Open all the TRV'S fully and close all the other "lockshield" valves on the rad's except the furthest one which is giving low heat. Open the furthest rad valves fully. Turn on the boiler/heating and see if this radiator heat up as it should within 5 minutes.

Then report back here the result.

Of course when you bleed a rad it will give you clear water as all the black sludge is at the bottom!
Forget about "boiling" the cylinder every 4 days it is not required.

60 degrees is hardly boiling!

freddyuk

It's in " " for a reason.;)