New combi - do I need weather comp or stick with Hive?

[wizbongre]

Likely going to have a new combi (Viessman or Intergas current forerunners) installed in the coming weeks to replace the existing Glowwom 30cxi which is getting like triggers broom.

Currently our heating is controlled by a Hive 'stat with TRV's on all radiators (and no wiring for a hard-wired thermostat.)

What would be the optimal control solution going forward? I'm getting different advice from different installers such as just keeping Hive and don't need weather compensation; keep Hive and use weather compensation; remove Hive and have weather compensation, etc, etc.

I'd like the best balance between comfort, ease of use and efficiency (obviously, like most customers I'd guess.)

Will weather comp work well with Hive?
Would I be better ditching Hive and getting something OpenTherm compatible?
Does OpenTherm control work well with weather comp?
Is there a difference in performance/efficiency between Viessman and Intergas in control capabilities?

Any other suggestions?

 

[muggles]

Chuck the Hive out - it's the least energy-saving of all the smart thermostats. Get a Honeywell T6 instead and connect it via OpenTherm to the boiler for best efficiency. That will give you location-based weather compensation and a much better smart control in one package. I'd recommend the Intergas boiler - not sure how the Viessmann would perform but I know Intergas works extremely well with this setup.

 

[wizbongre]

Thanks for the reply.

I’ve now had quotes from both Intergas and Viessmann installers (plus a couple of others) who both recommended sticking with the Hive and didn’t seem very enthusiastic about OpenTherm and WeatherComp. General consensus is to just stick with the Hive. (Also, Intergas was ~£1000 cheaper than Viessmann for similar job - Vitodens 100-W 35kW vs. Xclusive 36kW, both with powerflush and new filter.)

I’m leaning towards the Intergas but need to make sure the control solution is right - I could change this after but would prefer to do it from day 1, especially as it appears the Intergas needs an additional flue weather sensor for WeatherComp.

 

[muggles]

Sounds like a lack of understanding of the controls, sadly. OpenTherm is definitely worth having for best efficiency

 

[wizbongre]

And am I right to think I can get one of the Honeywell T6 ‘stats and use it wirelessly, ie I don’t have to run cable from the ‘stat to the boiler, as a direct replacement for my current Hive?

 

[mrStat]

And am I right to think I can get one of the Honeywell T6 ‘stats and use it wirelessly, ie I don’t have to run cable from the ‘stat to the boiler, as a direct replacement for my current Hive?

You need a T6R, it’s the same thing as the T6, but wireless

Good little stats, not the prettiest IMO, but reliable and because it’s Honeywell, the OpenTherm is pretty coded to perfection unlike some manufacturer’s grasps of the protocol.

Personally, I’d go Nest and OpenThern, but that’s because of looks and with the current Google climate and changes within the Nest framework, do seriously consider other options as I can see a lot of fallout from Google now taking an active interest in their baby project.

As for OpenTherm, very widely miss-understood within the heating industry. As @muggles said, if you can use it, do. May confuse the crap out of some heating engineers when they cannot get the thing on full rate, but that’s their problem. Why burn to 70 degrees when you may only need 50 degrees because it’s mild outside?

Boilers.... I think Viessmann are seriously over priced and over complicated for what they are, but then again, I do also have concerns about some Intergas features... Personally, if your installer is able to fix the thing and they come across good, nothing ultimately wrong with either.

 

[ericmark]

I would guess like most price is a consideration. Hive is rather expensive at £80 each for the TRV heads and no OpenTherm, Nest has OpenTherm and likely the cheapest of TRV heads (Energenie) but the TRV heads only follow, they don't tell the thermostat when to fire up boiler, EvoHome and Tado slightly more expensive TRV heads and I think both have OpenTherm.

There is a age thing with Hive, if old it may not work with new TRV heads.

As to if you need TRV heads that match main thermostat that is down to house design and your life style. You can get programmable heads for as little as £10 each, I have settled for 4 matched heads and 5 simple bluetooth heads, if not linked to main thermostat the head can't turn on the boiler, it can only stop a room getting too hot, it can't tell boiler to fire up.

Most the houses I have been involved with, up stairs the rooms seem to stay warm naturally and all that is needed is to stop them over heating.

The question I have asked and got no replies is which TRV head is best? With the main thermostat being much of a muchness, it's the TRV heads that can make or break the system. I have as said bought two, the expensive Energenie head does work, the twin sensors one for air and one for water the latter compensates the former once the lock shield valve is set, if set to 20°C does get room to 20°C, however it needs a phone, tablet, or computer to set them, plus hub, and does not have the open window feature which is found on the cheapest of cheap eqiva TRV head.

I selected Nest because already had 4 energenie heads and only two wires between where I wanted thermostat/control panel, to where valves and boiler was, I did not select it as being the best. I think likely with a clean slate it would have been EvoHome, but all the time we are getting upgrades and what was rubbish is no longer, I thought Hive was rubbish, but now they do the TRV's which link to main thermostat and actually turn it on, they are much better, though lack opentherm.

There is talk of being charged for IFTTT, as it stands using IFTTT I can program my TRV heads to read the weather and change temperature due to weather, but never done it, I like the idea of walking up to some panel on the wall and selecting a room and setting temperature even if I can do it with my phone.

 

[wwwebber]

Chuck the Hive out - it's the least energy-saving of all the smart thermostats.

You have said this before and it is not true. Whilst Hive is not Opentherm compatible it does have other TPI related energy saving features which others do not. Also spending a couple of hundred quid which would probably take decades to recoup is nuts.

Stick with Hive and focus on your schedule and the best use of your TRVs.

 

[wizbongre]

Thanks for all the further inputs to this - I’ll reply to them all when at a proper computer as have lots to digest and no doubt more questions...

For now I’m coming to the conclusion there’s no point changing controls right now - I’ll save the few hundred quid and stick with the Hive and see how it goes through the next winter. Might use the money to get the smart Hive TRV’s instead.

One last question for now - will Hive work with the weather comp sensor for the Intergas (part number 203207) and let the boiler manage flow temp when responding to the Hive’s simple on/off demand? As a non-installer I’m not 100% after reading the install manual.

 

[mrStat]

Intergas Xtreme manual

In principle, any on/off or OpenTherm room thermostat can be combined with an Intergas outdoor sensor. With an on/ off thermostat, the boiler will adjust the flow temperature according to the set heating line. With an OpenTherm thermostat, this determines the influence on the flow temperature.

As such, yes, you can keep your Hive and have weather compensation without any issues and save some £££s.

 

[ericmark]

I have heard it said that condensation boilers run most economic at flat out, at minimum output, and at midway point, it seems no one can make their mind up, so it seems uncertain if modulating thermostats or mark/space thermostats work best? However one thing that does seem to be proved, is the house is more comfortable when rooms stay at the temperature set, so the electronic TRV with the ability to be programmed is needed to ensure that comfort in all rooms of the house. And with a price label of £10 to £80 the question is how much do you want to spend?

I am sure EvoHome and Tado will work with any boiler in any home to give a room by room comfort zone as required, the question is with the boiler you have in the home you have with the live style you have, is there some thing cheaper that will do the job within what you want?

Currently our heating is controlled by a Hive 'stat with TRV's on all radiators

Does that mean Hive programmable TRV's or old wax TRV's?

At £10 each and 16 TRV heads that's £160 so every room runs it's own program, even with bluetooth so can be altered on phone or run in groups still only £15 each so £240, but once you start to link with a wall thermostat looking at £680 to £1280 for the heads, once you buy one make your tied to that make, so look at the cost of changing the TRV head to match the wall thermostat, not just the wall thermostat.

 

[Johnmdc]

@ericmark I don't know where you have got the figure of £80 for Hive TRVs. They are £54 each or you can buy a pack of 5 for £199, so £40 each.

 

[ericmark]

Clearly dropped in price since they first came out, it seems when a TRV head wants heat it triggers "Heat on Demand" for 30 minutes, and if after 30 minutes not up to temperature it triggers it again and so on. So if you have a hive TRV on many radiators each with a different schedule the wall thermostat becomes a simple switch turning the heating on when any TRV asks for heat, and off when no TRV needs heat as long as wall thermostat set lower than TRV's. So fact it does not have OpenTherm does not really matter, boiler will auto modulate with return water temperature.

With likes of EvoHome and Tado as far as I am lead to understand the TRV head tells the thermostat it needs hot water, and the thermostat sets the boiler output using OpenTherm. Using that method, before the boiler starts to cycle, it should already be at lowest temperature.

However so should a good boiler using just return water, where it gains is when the boiler does not have the built in algorithms to reduce the return water temperature as it output reduces.

So I am unsure how OpenTherm helps?

It would seem my Nest is now the poor Smart thermostat, although it has OpenTherm it does not take a command from the TRV to fire up boiler, one can use a follow command, but not sure how that helps? The whole idea is every room is individually controlled, so having 4 Energenie TRV's following the Nest means I have three rooms at always the same temperature, seems to be defeating the whole idea!

 

[vulcancontinental]

Try and think more about what you want to achieve. It's quite possible to operate an ON/OFF control at the same energy cost as a modulating control particularly if you have regular patterns of usage and a suitable boiler.

If you want remote control of the heating only and like Hive stick with it.
If you want remote control of the heating and the control to modulate the boiler use an Open Therm Control and or weather compensation but don't expect to save the planet.

If you want remote control of the heating, to modulate the boiler and but also have remote access to the boiler itself use a control from the boiler manufacturer as they're better integrated often.

As for Honeywell's perfect coding that's why their Evohome can't be used with many manufacturers combi's and the later range of thermostats had to be introduced that allowed domestic hot water temperature control because the early ones didn't. Anyway, the current ones are OK I'm led to believe.

 

[wizbongre]

Sounds like a lack of understanding of the controls, sadly.

I'm not going down this rabbit hole, save to say that I've been consistently disappointed at the apparent lack of knowledge of/interest in controls from the 6 engineers who have quoted for work so far. Feels like I know more (probably not of course!!) from Google - think I've just defined the most annoying customer trait ever! The installer I'm going with appears to have experience with WeatherComp at least (good & bad) and is a registered Intergas installer, plus he's just installed one for a mate who is happy.

Why burn to 70 degrees when you may only need 50 degrees because it’s mild outside?

My interpretation of Intergas manuals is that even with just Hive controlling in an on/off mode, the boiler will still use its WeatherComp in-flue sensor and modulate to some extent. It supposedly also learns patterns of usage, which might be interesting...

Boilers.... I think Viessmann are seriously over priced and over complicated for what they are, but then again, I do also have concerns about some Intergas features... Personally, if your installer is able to fix the thing and they come across good, nothing ultimately wrong with either.

Agreed completely. After getting 6 quotes across Viessmann and Intergas, I'd suggest Viessmann are eye-wateringly expensive (or their installers are.) Their base model 050 installed by a registered agent comes in at way over £1000 more than higher model Intergas. You do often get what you pay for of course so I may regret this consideration... Bear in mind from my perspective and that of the 6 engineers who have quoted, my request is an easy job as its basically a case of removing the old boiler and installing the new one in place. Pipework, gas supply, etc. are all relatively new and in good state.

Most the houses I have been involved with, up stairs the rooms seem to stay warm naturally and all that is needed is to stop them over heating.

Our house is of post-war solid wall construction, and due to the layout most rooms have 3 outside walls. It does not retain heat well! As a result, and due to orientation, my daughter's bedroom can drop to a much lower temp. than the rest of the house overnight - my plan is to use the Hive TRV's to keep her room from freezing without the system heating the rest of the house unnecessarily. It will take a bit of faffing with Hive settings but should be worth it.

Also spending a couple of hundred quid which would probably take decades to recoup is nuts.

Stick with Hive and focus on your schedule and the best use of your TRVs.

This is where I've got to - no point swapping Hive (especially as I have a ton of other Hive stuff around the house and it all works with Alexa too.)

Intergas Xtreme manual


As such, yes, you can keep your Hive and have weather compensation without any issues and save some £££s.

Yes, thanks - I re-read it and agree it looks like I will still see benefit.

Does that mean Hive programmable TRV's or old wax TRV's?

Currently got liquid TRV's - Danfoss RAS 2's that I fitted throughout the house last year - and I'll gradually replace the Danfoss heads with new Hive ones. Whilst not cheap, the control it will allow us, both for the temp differences across rooms I mention above, plus the fact I work random hours, will be worth it.

However so should a good boiler using just return water, where it gains is when the boiler does not have the built in algorithms to reduce the return water temperature as it output reduces.

Agreed - and this is where I think I should see some benefit from the inbuilt logic of the Intergas.

Try and think more about what you want to achieve. It's quite possible to operate an ON/OFF control at the same energy cost as a modulating control particularly if you have regular patterns of usage and a suitable boiler.

If you want remote control of the heating only and like Hive stick with it.
If you want remote control of the heating and the control to modulate the boiler use an Open Therm Control and or weather compensation but don't expect to save the planet.

If you want remote control of the heating, to modulate the boiler and but also have remote access to the boiler itself use a control from the boiler manufacturer as they're better integrated often.

Good summary. To your first point, when we moved in we inherited gas/electric suppliers from the previous family. They were both NHS workers doing differing shift patterns and had 3 kids below teenage years. We are a family of four, with equally random heating requirements. Nearly 7 years ago when we moved in we were given an estimate of ~£350/month for gas/electric. Since then I've installed a wireless 'stat and then upgraded to Hive to replace the original clock on the boiler; installed TRV's all round the house; insulated the loft; bought the wife and kids bigger jumpers... We pay ~£145/month now. I don't actually expect a new boiler and controls to massively impact that.