Nest Learning thermostat with smart TRVs e.g. Tado

The above about TRVs also applies if you have decent first party controls on a gas boiler. Nest/tado/hive destroy the efficiency of a well set up condensing gas boiler with weather compensation.

robj20 said:
How is that even remotely efficient then.
It's always going to be better to heat only the space you need when you need it.
If you can't have it heating only one room then surely it's the wrong size heatpump.
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reducing the amount of available capacity in the system means the boiler or heat pump cycles more often (on, off, on, off etc) and this cycling destroys efficiency because it uses a bit load of energy. They can only modulate down so low when they also have to ramp up to cover demand at -5c outside.

If you are in your house regularly, you are better off tricking in the heat low and slow across all radiators. Using set back temperatures rather than turning off completely. If you turn it off, let the house cool (but not long enough to cool fully) the boiler will ramp up to maximum capacity to heat the space back up again in a short period which often burns more gas than the low and slow method.

If you have other heat sources like the log burner above then of house that changes things again.
 
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b0rn2sk8 said:
The above about TRVs also applies if you have decent first party controls on a gas boiler. Nest/tado/hive destroy the efficiency of a well set up condensing gas boiler with weather compensation.


reducing the amount of available capacity in the system means the boiler or heat pump cycles more often (on, off, on, off etc) and this cycling destroys efficiency because it uses a bit load of energy. They can only modulate down so low when they also have to ramp up to cover demand at -5c outside.

If you are in your house regularly, you are better off tricking in the heat low and slow across all radiators. Using set back temperatures rather than turning off completely. If you turn it off, let the house cool (but not long enough to cool fully) the boiler will ramp up to maximum capacity to heat the space back up again in a short period which often burns more gas than the low and slow method.

If you have other heat sources like the log burner above then of house that changes things again.
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So your saying heating the whole house 24/7 is more efficient than heating one or two rooms only during the day?
It's certainly not in my experience.
Even with my gas boiler cycling which it does but in a controlled manner IE cycle duty set to 4 times per hour minimum on time set appropriately. It really doesn't use much gas and the few tubes I've run the maths a heatpump would cost more and makes no sense.

I'm guessing do many people are comparing a week setup heatpump that's running fairly well to a hugely inefficient gas setup and that's when the maths adds up. I reckon my gas boiler runs colder than some heatpumps at the minute. Especially when it gets really cold and the boiler is on its lowest setting 100% of the time.
 
@Coran - does that not mean that your heat pump output is rated too highly for your house?

@robj20 - probably depends too much on the individual circumstances of the house but some boilers can modulate down to a lot lower output to keep the house at a constant temperature. There will be cases though where just blasting the heating for an hour or two once or twice a day is just as efficient.

There’s a good video about it here:

 
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Stu999 said:
@Coran - does that not mean that your heat pump output is rated too highly for your house?
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I think I need to wait for colder weather to see. Heating 1-2 rooms whilst at over 10C overnight is very low demand compared to heating the house when it’s -2C outside. This is what they spec them for.

I’m still enjoying figuring out how best to use it - it was 300% efficient when running just 1-2 rooms that dipped below the minimum temp overnight but has regularly been well over 400% when it gets into a good rhythm.
 
maybe OP already has them, but Pressure independent control valves would be my investment before investing extensively in sexy smart trv's, so that that the flow is balanced if you only have a few radiators on.

From previous home assistant discussions thought that some of the smart trv's do allow valve opening percentage to be controlled though, which would allow some balancing
 
jpaul said:
maybe OP already has them, but Pressure independent control valves would be my investment before investing extensively in sexy smart trv's, so that that the flow is balanced if you only have a few radiators on.

From previous home assistant discussions thought that some of the smart trv's do allow valve opening percentage to be controlled though, which would allow some balancing
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Evohome kind of does it, as it learns how a room heats up it knows at what percentage to open the valve. If you have multiple on it'll open a valve to more Vs only one radiator on.
But those self balancing valves still seem to be the best way of doing it. As I redecorate ill be swapping to them.
 
Been thinking about installing something similar to Nest/Hive/Tado but I don't know much about them.

Do they all have the ability to switch on individual radiators fitted with Smart TRV's, when required? We have 12 radiators inc towel radiators in our main bathroom and en-suite. Can you, via the apps or control panels control them independently on demand, or do only some systems have that ability?

Also, does anyone know what a ball park installation by a professional would cost (given I'll need 12 x Smart TRV's plus the actual system)?

Ta.
 
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Draeger said:
Been thinking about installing something similar to Nest/Hive/Tado but I don't know much about them.

Do they all have the ability to switch on individual radiators fitted with Smart TRV's, when required? We have 12 radiators inc towel radiators in our main bathroom and en-suite. Can you, via the apps or control panels control them independently on demand, or do only some systems have that ability?

Also, does anyone know what a ball park installation by a professional would cost (given I'll need 12 x Smart TRV's plus the actual system)?

Ta.
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Installation: If you have TRVs, then they just screw off by hand (doesn't let any water out) and new ones screw on.

Cost: sadly cheapest I've seen smart TRVs is £40-50. So you're looking at perhaps £600 or so in parts.
 
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LuckyBenski said:
Installation: If you have TRVs, then they just screw off by hand (doesn't let any water out) and new ones screw on.

Cost: sadly cheapest I've seen smart TRVs is £40-50. So you're looking at perhaps £600 or so in parts.
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Agreed.
No need for professional install.

I bought my tado Trvs for under 40 each. But they've gone up since then.

Yes. Each radiator can be controlled independently
 
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Draeger said:
TRV's would be straightforward enough to install, I'm not sure about the wiring on the thermostat and programmer units though, is that fairly straightforward?
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It's very basic or fairly basic - if you've just got a combi boiler and no tanks, it's literally 2 or 3 wires. Obviously safety practise applies here i.e. cut power to the boiler or, if you're cautious, just turn the house off for 15 min.
 
LuckyBenski said:
It's very basic or fairly basic - if you've just got a combi boiler and no tanks, it's literally 2 or 3 wires. Obviously safety practise applies here i.e. cut power to the boiler or, if you're cautious, just turn the house off for 15 min.
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Mine was about 10 wires (3 into one hole!)

It was only tricky as I didn't have much slack wire to work with. But as long as you are careful and label the wires (tado came with labels) it's all ok

Not my pic.. But mine looked like this!
aMKpVv9.jpg
 
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dirtychinchilla said:
I wonder how long it'll take to save £600. That's quite a lot of gas
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It's a comfort thing as well. The better systems will maintain an even temperature rather than overshooting all the time.
I had to redo our whole central heating so I just spent the extra at that time to go for smart heating.
You don't have to add trvs to every radiator all at the same time either.
 
robj20 said:
It's a comfort thing as well. The better systems will maintain an even temperature rather than overshooting all the time.
I had to redo our whole central heating so I just spent the extra at that time to go for smart heating.
You don't have to add trvs to every radiator all at the same time either.
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Agree it's about making the home more comfortable, and possibly more efficient too so saving a bit of energy for environmental reasons.

One thing to note though is if you don't have a smart thermostat to activate the boiler from the smart TRVs, then the non-smart radiators will still get hot and waste heat whenever the boiler runs.
 
LuckyBenski said:
Agree it's about making the home more comfortable, and possibly more efficient too so saving a bit of energy for environmental reasons.

One thing to note though is if you don't have a smart thermostat to activate the boiler from the smart TRVs, then the non-smart radiators will still get hot and waste heat whenever the boiler runs.
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I think I've posted this before (maybe last year) but I only used them in rooms I DIDN'T want hot, and those that were critical.

So we ended up with 1 in the nursery (room too cold - only this guy could activate the heating) and then 2 in the rooms that would get uncomfortable if the nursery came on (usually at night, as that was a north facing cold room). I'm not sure you'd ever get return on investment just carpet bombing them everywhere. Although when I moved into this house I found 3 more smart TRVs I had forgotten I had bought lol. So to contradict myself, I have them in every room upstairs and just one downstairs.
 
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dlockers said:
I think I've posted this before (maybe last year) but I only used them in rooms I DIDN'T want hot, and those that were critical.

So we ended up with 1 in the nursery (room too cold - only this guy could activate the heating) and then 2 in the rooms that would get uncomfortable if the nursery came on (usually at night, as that was a north facing cold room). I'm not sure you'd ever get return on investment just carpet bombing them everywhere. Although when I moved into this house I found 3 more smart TRVs I had forgotten I had bought lol. So to contradict myself, I have them in every room upstairs and just one downstairs.
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Nailed it then! I've been sat on the smart TRVs idea hoping the prices come down for a year. At first it seemed like a really fiddly setup deciding which rads to do, but today I've had a few chats that made it make more sense :)
 
dlockers said:
I think I've posted this before (maybe last year) but I only used them in rooms I DIDN'T want hot, and those that were critical.

So we ended up with 1 in the nursery (room too cold - only this guy could activate the heating) and then 2 in the rooms that would get uncomfortable if the nursery came on (usually at night, as that was a north facing cold room). I'm not sure you'd ever get return on investment just carpet bombing them everywhere. Although when I moved into this house I found 3 more smart TRVs I had forgotten I had bought lol. So to contradict myself, I have them in every room upstairs and just one downstairs.
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Yes you did.

For me it's comfort too. Also posted about this.


The old stat was in the east facing hall/entrance.
And my office is in the west.
So the evening sun would be against my window heating it up. And the stat would say "ooh it's cold in the east hall, turn that heating on".

I'd suddenly. Find myself roasting and the radiator was on!
I don't want to be paying for sweaty balls
 
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