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Thread: EvoHome without HR92 smart TRVs?

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    Default EvoHome without HR92 smart TRVs?

    In a very long thread about noisy smart TRVs, one person mentioned the idea of using a different way to control radiators... Wired devices not using noisy gears.

    I've also been wondering about a less visually obtrusive setup for my period style radiators as the HR92 units are seemingly large and plastic.

    The concept of a room thermostat and a radiator valve controlled from the central unit comes up, but I've no idea what other options than an HR92 exist. It does seem over the top to have multiple sensors in a room especially if there are multiple radiators, but thermostats are as expensive as HR92 units.

    The website didn't seem to cover this idea, is it possible and if so, how?

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    I personally would stick with HR92's... Certainly no other method I can think of would be more effective at controlling room temperature. Who said they were noisy?

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    There's a long-running thread about it. Several people talking about modifying their TRVs or insulating them. Stuffing towels behind radiators, etc. The consensus was HR92s are quiet compared to other motorised TRVs but still make a noticeable noise.

    I thought your own advice was that a separate room thermostat was better for monitoring room temperature, leaving the HR92 as just an actuator. I know you sell them for that purpose
    But I also have the issue of aesthetics. I've seen the HR91 as a slightly less ugly model though they are not widely known it seems.

    But I was wondering if EvoHome is compatible with any kind of wired valve actuator (from yourselves or others). e.g. have a room thermostat paired with some other valve actuator - either on the radiator or on the supply pipe itself. I think EvoHome can talk to generic on/off switches (for electric heaters) so in principle it seems possible but a bit Heath Robinson unless you have RF motorised control valves?! I came across TR4/TR8 I think they were called but there was no explanation how they are controlled.

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    Quote Originally Posted by MrBoy View Post
    There's a long-running thread about it. Several people talking about modifying their TRVs or insulating them. Stuffing towels behind radiators, etc. The consensus was HR92s are quiet compared to other motorised TRVs but still make a noticeable noise.
    I think people's expectations exceed reality sometimes... End of the day a HR92 is a DC motor driven TRV and verses liquid or wax expansion TRV's anything is going to be 'noisy'. I think they are very quiet personally when you look at other DC motor driven items, like radio controlled cars, etc...

    Quote Originally Posted by MrBoy View Post
    I thought your own advice was that a separate room thermostat was better for monitoring room temperature, leaving the HR92 as just an actuator. I know you sell them for that purpose
    But I also have the issue of aesthetics. I've seen the HR91 as a slightly less ugly model though they are not widely known it seems.
    An additional room thermostat in a room containing more than 1x HR92 or where the HR92 is blocked in by something is good advice... If the HR92 and radiator it is attached to has good and free flowing air movement then no requirement for an additional sensor in the zone.

    Quote Originally Posted by MrBoy View Post
    But I was wondering if EvoHome is compatible with any kind of wired valve actuator (from yourselves or others). e.g. have a room thermostat paired with some other valve actuator - either on the radiator or on the supply pipe itself. I think EvoHome can talk to generic on/off switches (for electric heaters) so in principle it seems possible but a bit Heath Robinson unless you have RF motorised control valves?! I came across TR4/TR8 I think they were called but there was no explanation how they are controlled.
    As for the idea of using thermal actuators as 'radiator controllers', my personal view is that this is a bad idea. Reason behind this is that radiators are a fast response technology and thermal actuators are slow responding (4 minutes to open and close). The HR92's make changes to the radiator valve pin position based on room temp demand... The best a thermal actuator is going to do is be on or off which will have an impact on room comfort (overshoots very likely).

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    One solution might be to use the wired actuators used mainly in the underfloor heating manifolds. Eg the Honeywell MT8 has been previously mentioned , but there are plenty of similar brands. These open slowly and are silent ( I am using 8 in our ufh system ). You could drive them by wiring back to a Honeywell underfloor heating controller , eg HCCR80. The main issues are the system dynamic and whether the controller would be able to learn sufficiently. These actuators are either fully open or fully closed, unlike the HR92s that can open at any position. . Also Im not sure how much system dynamic control is included in the HCC, or whether all the learning is done in the evo controller. In addition youd need a separate thermostat per zone .

    The HCC can be set up to group ( in this case) radiators into HCC zones( I prefer to call them ports to avoid confusion with evo controller zones ) and then one or more of these ports can be controlled by an evo controller zone. Its not a cheap option , plus there would be all the wiring to do !!
    Last edited by rvb99; 7th December 2017 at 07:43 AM.

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    Quote Originally Posted by rvb99 View Post
    One solution might be to use the wired actuators used mainly in the underfloor heating manifolds. Eg the Honeywell MT8 has been previously mentioned , but there are plenty of similar brands. These open slowly and are silent ( I am using 8 in our ufh system ). You could drive them by wiring back to a Honeywell underfloor heating controller , eg HCCR80. The main issues are the system dynamic and whether the controller would be able to learn sufficiently. These actuators are either fully open or fully closed, unlike the HR92s that can open at any position. . Also I’m not sure how much system dynamic control is included in the HCC, or whether all the learning is done in the evo controller. In addition you’d need a separate thermostat per zone .

    The HCC can be set up to group ( in this case) radiators into HCC zones( I prefer to call them ports to avoid confusion with evo controller zones ) and then one or more of these ports can be controlled by an evo controller zone. It’s not a cheap option , plus there would be all the wiring to do !!
    As I have already said above this method won't work effectively with radiators...

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    Has it been tried ? The Honeywell publicity includes an example of a MT8 fitted to a radiator . Moreover just because an actuator is slow acting or only has an open / shut position does not mean the system will over shoot. What is more important is the design of the control system and the open/feedback parameters/gains and, if used, their derivatives . The compromise generally being that to avoid overshoot the ramp up / down may be slower. In learning systems of course the other factor is the elasticity given to these parameters to adjust.

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    I find the HR92 very noisy, little disappointing to be honest. I had to alter my times for the bedroom one as it was waking me up when it first turned on in the morning, so its now set for when my alarm goes off.
    I regret not going the actuator and bdr91, plus thermostat on the wall route for the bedrooms.

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    If you have the ability to group up some radiators within a zone then using an motorised zone valve for those radiators may be an option. There are many houses plumbed this way before per radiator control was viable. You can then have a BDR91 control that motorised zone valve. You can ofcourse go all out and have a motorised zone valve per rad too.

  10. #10
    Automated Home Ninja Dan_Robinson's Avatar
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    The mt8 is also controllable with pwm. Becareful what you interpret from a picture. You're not privy to all the information behind the scenes, and neither was the person writing the literature.

    Yes I am currently running this system at home but I also have some issues with the way it works with OpenTherm. Whether they're related or I have another issue is another matter (actuators controlled through the Hcc80. I don't have overshoot,, but the boiler doesn't modulate as I would expect. However z I also have an undersized emitter in a bathroom which I'm planning on addressing at some point.

    Looking forward to the software update to see what's going on more clearly.
    Kind Regards - Dan Robinson (Jennings Heating Ltd)

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