Best Wifi enabled thermostat

[KTF]

8.4L 154 said:

Are the bathroom rads lockshields wide open?

They are next on my list. I was going to check the one in the en-suite anyway as whilst the radiator gets warm the room still feels cold which is a bit strange.

Whilst the system was 'balanced' as part of the power flush, I might as well just gone round and done it myself as now I am going to have to check it anyway.

Anyway, since tweaking the one in the hall, all the downstairs rooms feel warm where before the rooms were warm but the hall was cold. Granted its based on feel only but seems better.

[Trustmeimadoctor]

KTF said:

Trustmeimadoctor said:

all i can say is
its not easy being green....

i have leaned a lot this year from playing around with this stuff.
and when you get a win its good

but yeah as i said earlier your radiator was too small not physically but as it was restricting the flow below what is required to provide x watts of energy you need
say your needing 800w of energy at 0 to maintain your temp then 801 wil make it increase very very slowly 900 will heat it up even faster but your rad can only physically give out a certain amount of energy at a given flow


what size and type of rad is it? 2-panel fins on both sides?

640 x 700. Single panel with fins at the back. Mid-80s as it’s original to the house.

that rad needs 26L/h at 75 c flow 55 return

[Trustmeimadoctor]

KTF said:

Trustmeimadoctor said:

all i can say is
its not easy being green....

i have leaned a lot this year from playing around with this stuff.
and when you get a win its good

but yeah as i said earlier your radiator was too small not physically but as it was restricting the flow below what is required to provide x watts of energy you need
say your needing 800w of energy at 0 to maintain your temp then 801 wil make it increase very very slowly 900 will heat it up even faster but your rad can only physically give out a certain amount of energy at a given flow


what size and type of rad is it? 2-panel fins on both sides?

640 x 700. Single panel with fins at the back. Mid-80s as it’s original to the house.

that rad needs 26L/h at 75 c flow 55 return to give its max 610w of output

[KTF]

Trustmeimadoctor said:

that rad needs 26L/h at 75 c flow 55 return to give its max 610w of output

The flow is set to 70 so would that change the numbers? How do you calculate the L/h value as I would like to have a go at getting it set properly.

[Trustmeimadoctor]

70/50 is 22l/h

download the danfoss installer app it gives you all the tools

[Sheepshanks]

Trustmeimadoctor said:

that rad needs 26L/h at 75 c flow 55 return to give its max 610w of output

I can never get the spec'd drops across rads and, with our old system, I spent a lot of time trying balance rads.

With TRVs (especially motorised TRVs) and modern boilers with variable pumps, isn't balancing a bit pointless? Surely it all goes out of the window as you have various TRVs on different schedules, and those that are on start to close pretty quickly. Then the pump speed varies itself according to demand to mess things up further.

I've got everything fully open on our new system apart from the bathroom rads, which don't have TRVs, so I backed them off so they get comfortably warm, and, somewhat oddly, the landing rad was getting hot much faster than anything else. Our bedroom one heats up pretty quickly too, but that's useful in the morning and it fairly quickly turns itself off.

[B'stard Child]

KTF said:

Trustmeimadoctor said:

all i can say is
its not easy being green....

i have leaned a lot this year from playing around with this stuff.
and when you get a win its good

but yeah as i said earlier your radiator was too small not physically but as it was restricting the flow below what is required to provide x watts of energy you need
say your needing 800w of energy at 0 to maintain your temp then 801 wil make it increase very very slowly 900 will heat it up even faster but your rad can only physically give out a certain amount of energy at a given flow


what size and type of rad is it? 2-panel fins on both sides?

640 x 700. Single panel with fins at the back. Mid-80s as it’s original to the house.

What's the Hallway floor area and height of the walls - does it have any external walls/Doors Windows?

Example my hallway is 31.9 m3 - the original rad (1982 build was T11 800 x 600 = 2,815 BTU/Hr with a Delta 60)

I replaced with T22 800 x 600 output = 4,113 BTU/hr at a Delta of 50

[Trustmeimadoctor]

Sheepshanks said:

Trustmeimadoctor said:

that rad needs 26L/h at 75 c flow 55 return to give its max 610w of output

I can never get the spec'd drops across rads and, with our old system, I spent a lot of time trying balance rads.

With TRVs (especially motorised TRVs) and modern boilers with variable pumps, isn't balancing a bit pointless? Surely it all goes out of the window as you have various TRVs on different schedules, and those that are on start to close pretty quickly. Then the pump speed varies itself according to demand to mess things up further.

I've got everything fully open on our new system apart from the bathroom rads, which don't have TRVs, so I backed them off so they get comfortably warm, and, somewhat oddly, the landing rad was getting hot much faster than anything else. Our bedroom one heats up pretty quickly too, but that's useful in the morning and it fairly quickly turns itself off.

thats why you need auto balancing trv's variable pump is another spanner in the works though

really the output of the rad is set by the amount of water flowing through it and the water temp

if you lower the flow volume but keep the temp the same the output drops
if you lower the temp but keep the flow the same the output drops
both these can be worked out with maths and they scale in a predictable way

in theory with good boiler controls it should know if your have flow return delta 20 then if the return is above that it needs to maintain the 20 so will lower the flow temp if its below 20c difference and raise it if its above

Edited by Trustmeimadoctor on Monday 23 January 17:02

Edited by Trustmeimadoctor on Monday 23 January 17:04

[8.4L 154]

Sheepshanks said:

Trustmeimadoctor said:

that rad needs 26L/h at 75 c flow 55 return to give its max 610w of output

I can never get the spec'd drops across rads and, with our old system, I spent a lot of time trying balance rads.

With TRVs (especially motorised TRVs) and modern boilers with variable pumps, isn't balancing a bit pointless? Surely it all goes out of the window as you have various TRVs on different schedules, and those that are on start to close pretty quickly. Then the pump speed varies itself according to demand to mess things up further.

I've got everything fully open on our new system apart from the bathroom rads, which don't have TRVs, so I backed them off so they get comfortably warm, and, somewhat oddly, the landing rad was getting hot much faster than anything else. Our bedroom one heats up pretty quickly too, but that's useful in the morning and it fairly quickly turns itself off.

Guess it depends if you like the order rooms warm up in. I think the variable speed pumps go someway to mitigating varying pressures in the system as TRVs close but you still need a somewhat balanced system to get rooms to warm up together or else you relying on the least resistance TRV closing before heat goes elsewhere.

I do wonder what the impact of variable speed pumps are on auto balancing TRVs though. I'm guessing they would be better off with constant speed and let the auto balance trv do its thing rather than them start fighting each other

[Trustmeimadoctor]

Yeah
There isn't a huge amount I can find out there about it

[Sheepshanks]

Trustmeimadoctor said:

thats why you need auto balancing trv's variable pump is another spanner in the works though

I thought auto-balancing TRVs don't really work with variable pumps?

[Trustmeimadoctor]

Sheepshanks said:

Trustmeimadoctor said:

thats why you need auto balancing trv's variable pump is another spanner in the works though

I thought auto-balancing TRVs don't really work with variable pumps?

Depends it seems on variable speed or variable pressure as to how you do things but yeah they are harder

[KTF]

B'stard Child said:

What's the Hallway floor area and height of the walls - does it have any external walls/Doors Windows?

Example my hallway is 31.9 m3 - the original rad (1982 build was T11 800 x 600 = 2,815 BTU/Hr with a Delta 60)

I replaced with T22 800 x 600 output = 4,113 BTU/hr at a Delta of 50

Its the original radiator and I realise that the newer ones are more efficient. The single radiator is downstairs away from the front door but has to cover the whole hallway as there is no radiator upstairs. The room stat is closer to the front door.

You can see it in this picture here taken with the front door behind where the photo was taken from:



All room doors are kept closed and the Honeywell dial room stat is where the Tado stat now is.

Anyway, after adjusting the lockshields on the radiator the temperature is climbing better but its still very hard to tell like for like as Tado keeps turning the damn boiler off where I would still expect it to be on constantly with a low flame until the target temperature is reached.

Still debating putting the old dial stat back on for a day and seeing what that does as I still dont think the boiler should be cycling on and off (correct me if I am wrong).

[Trustmeimadoctor]

KTF said:

B'stard Child said:

What's the Hallway floor area and height of the walls - does it have any external walls/Doors Windows?

Example my hallway is 31.9 m3 - the original rad (1982 build was T11 800 x 600 = 2,815 BTU/Hr with a Delta 60)

I replaced with T22 800 x 600 output = 4,113 BTU/hr at a Delta of 50

Its the original radiator and I realise that the newer ones are more efficient. The single radiator is downstairs away from the front door but has to cover the whole hallway as there is no radiator upstairs. The room stat is closer to the front door.

You can see it in this picture here taken with the front door behind where the photo was taken from:



All room doors are kept closed and the Honeywell dial room stat is where the Tado stat now is.

Anyway, after adjusting the lockshields on the radiator the temperature is climbing better but its still very hard to tell like for like as Tado keeps turning the damn boiler off where I would still expect it to be on constantly with a low flame until the target temperature is reached.

Still debating putting the old dial stat back on for a day and seeing what that does as I still dont think the boiler should be cycling on and off (correct me if I am wrong).

it will do if your arnt getting rid of enough heat from the water as the water returning will be too hot so it will shut down to let it cool really you could do to measure the pipes under the boiler and see the difference between flow and return really should be around 20c

i can only manage about 8c at the moment



but also it is possible the boiler just cant modulate down low enough to stop its self cycling the water that is the main reason mine cycles as my minimum its 12kw yet i only need 6.5 at -3 and its not -3 today so it shuts off to stop it heating it up too much

Edited by Trustmeimadoctor on Tuesday 24th January 10:12

[KTF]

The heating pump is on speed 1 (of 3) and there are 13 rads in the system.

With a flow of 70c, after going round 13 rads all emitting heat (at least initially before the TRVs close them off), I would be very surprised if the return would still be around 70 meaning the boiler would have to shut down as it the flow temp is too high.

However it is something else to measure to try and understand what is going on.

[paralla]

KTF said:

The heating pump is on speed 1 (of 3) and there are 13 rads in the system.

With a flow of 70c, after going round 13 rads all emitting heat (at least initially before the TRVs close them off), I would be very surprised if the return would still be around 70 meaning the boiler would have to shut down as it the flow temp is too high.

However it is something else to measure to try and understand what is going on.

The best insight you are going to get is by measuring your flow temps. You haven't measured your flow temps but are asking what else you can measure.

You can get a non-contact Laser IR Infrared Thermometer for £20 from Amazon
https://www.amazon.co.uk/Etekcity-Lasergrip-Non-co...

[Trustmeimadoctor]

you could be surprised how hot it still is as you quite possibly dont need 70c heat at the moment anyway and its likely your boiler is to big for your house too so it all just adds up

[KTF]

paralla said:

You can get a non-contact Laser IR Infrared Thermometer for £20 from Amazon
https://www.amazon.co.uk/Etekcity-Lasergrip-Non-co...

Thats what I have. Going to get it out of the garage then do some measuring.

[Trustmeimadoctor]

also remember the water doesnt go from one rad to the next to the next it goes to all of them at the same time through the rad and back down the return unless you have a one pipe system

[KTF]

Trustmeimadoctor said:

really the output of the rad is set by the amount of water flowing through it and the water temp

if you lower the flow volume but keep the temp the same the output drops
if you lower the temp but keep the flow the same the output drops
both these can be worked out with maths and they scale in a predictable way

Interesting as what I have read seems to suggest that you should have the pump on the lowest speed you can get away with. i.e. set it to the lowest and if all radiators get hot then that should be ok. If its too high then the water temp may not actually drop enough on the return and the boiler cuts out?

I also thought that if the water was flowing through the system slower then more heat would be radiating out the radiators as its 'sitting there' for longer but I guess thats not the case?

My pump is on speed 1 and, as mentioned before, the boiler seems to keep cutting in and out. I was keeping an eye on it this morning and wondered if it was due to the return temp and flow rate based on the above and what you have said before.

After its initial burn in the morning from the overnight setback temperature, the boiler would come on, very quickly heat up to the set flow temp of 70 but then continue past that to 71/72 and shut off again. Then it would come back on and repeat every 10 minutes or so.

I have now changed the pump speed to 2 and now the boiler is coming on, heading up to 70c more slowly and then sitting there modulating the flame up and down to maintain the temp rather than shutting off like it was doing before.

The next question I guess is whether this is actually more economical having it sitting on 70 and a low flame rather than cutting in and out every 10/15 mins. But then the flip side is that the house will heat up faster so it may not need to be on for as long.

When I switched the pump from 2 to 1, it did save gas but I did notice the house was slower to heat up. I sometimes wonder if its better just to be like 'normal' people who dont worry about stuff like this. However the geeky/engineer part of my brain cant help but tweak...

After adjusting the radiator, the downstairs seems much more balanced now as the hallway now feels a similar temperature to the other rooms where it was noticeably cold before so it looks like progress has been made there. Annoying though as if I had realised it sooner I would have saved a lot more in gas over the cold snaps