Evohome, House Heat, Conrad, Heatmiser, Hometronic..... Arrrrrgggghhhhh Help Please

[vetinry]

Hello everyone

This is my first post here, although I have been reading posts for a while now.

I hope that some of the many experts on the site might be able to help with some general questions and a specific case study, which is my house.

2 years ago, we purchased a large (3200 sq ft), sprawling house, which was being heated by oil on a simple Y plan system.

Since then, I've already made some modifications but am still not fully happy with the results.

The first key change was to remove the DHW from the oil based system and now our hot water requirements are supplied by an Ecocent cylinder, which is effectively a mains pressure cylinder with an air source heat pump on top, which recovers hot, moist air from our bathroom and produces more hot water.

Our previous oil bill was approx £2500, and during the summer months, when no heating was on, I calculated that DHW was costing about £2 per day. I've put an energy meter on the ecocent and now the DHW bill is about £3.50 per week. Clearly when the heating is on, I'm guessing that there is some sharing of boiler resources and so I know that the saving will not be quite as high during winter months, but all in all I'm happy.

The next change to the system was to introduce some zones. We now have 3 zones, 1 for the UFH in the open plan Kitchen / Dining Room and Utility, another zone for upstairs, and another for the remainder of downstairs.

There are 3 Honeywell CM907 wired programmable thermostats controlling the zone valves, one in the kitchen and the others in upstairs and downstairs hall

In addition to the Kitchen area, there are 5 bedrooms, 4 bathrooms, 2 lounges, a study, conservatory and an upstairs and downstairs hall to heat and we have a mixture of UFH, radiators, thermal skirting and probably soon a couple of fan convectors.

Due to the original pipe design, it's not easy to seperate the downstairs rooms as I would like. 3 of the bedrooms and bathrooms are downstairs, and they are on the same zone as the living rooms.

Downstairs, the hall is always colder than other rooms and the radiator is inadequate. This means that during colder days, the thermostat rarely achieves it's required temperature and so heat is permanently being called for. All of the radiators in the downstairs rooms with the exception of one of the bathrooms have Drayton TRV4s so the rooms themselves are kept at a reasonable temperature.

Upstairs, the reverse is true - the thermostat on the landing seems to reach it's temperature quite easily and therefore the upstairs zone switches off before the rooms are properly heated. Each of the upstairs bedrooms has thermal skirting.

We now have a baby boy and my wife wants better temperature control in the upstairs rooms. I think that I can reasonably easily solve this using a wireless thermostat upstairs and just keep it in whichever room the baby is in.

But, since there are other issues with the system, I would like to try and improve overall control.

This is where the title of my thread comes in. Now that I've started looking, it's clear that there are many options available and I just want to try and ensure I make a good decision for my house.

I like the apparent simplicity of the Evohome system, but it's relatively expensive. Plus I'm not sure whether having the temperature being read next to the radiator is the best option. Also my thermal skirting, which is in the upstairs rooms doesn't have TRVs. I can add a TRV body into the pipework outside the room but then it won't be reading the room temp and so a thermal actuator linked to the thermostat in the rooms seems to make more sense.

I also like the idea of having thermostats in each of the rooms / zones that I need better control. But the house heat solution doesn't appear to have any central control.

Conrad make 2 systems - FS20 and another. Are these the same as the house heat products. If so, there appears to be central control available but then there are limitations for number of time points / set back etc.

Honeywell also make a hometronic system - is this still current and how does it differ to Evohome?

And then there is Heatmiser, and no doubt countless others.

Finally, I'm confused by how my existing zone valves work with these systems. I purposely wanted to split the house into smaller chunks to avoid having to pump hot water around the pipework unecessarily but now I'm not sure if they can still function properly with any of these systems.

I appreciate that there are lots of questions here and really hope that some of you can help me to answer them.

Best wishes

Steve

[SensibleHeatUK]

The Honeywell Radiator Controllers can be used with a separate battery-powered wall-mounted room sensor if you worried about the accuracy of measuring the temperature that close to the radiator. However in reality the strong convection currents created by the radiator mean that the built-in sensor still works effectively in the majority of cases providing the radiators are not behind heavy curtains, furniture, or inside cabinets.

Evo is an 8-room heating controller and Hometronic has 16 heating zones plus upto 32 channels of time-only control. However the Hometronic Manager is about twice the cost of Evo, therefore you could use two Evo controllers for whole-house control for the same price. And Evo does have the benefit of improved control over switch modules (that you might6 use for rooms with underfloor heating to avoid using the full Manifold Controller), and gives greater opportunity to control your existing zone valve (by having an Evo for each radiator zone valve with the rooms allocated accordingly).

The improved zone control and much more efficient temperature measurement and room temperature control should save you around a third of your remaining heating bill, so although it is a costly upgrade there will also be a decent payback based on energy saved.

[vetinry]

Thanks for your response.

That makes sense with regards to the convection of the radiators, I guess I could just start with the radiator controllors and see how I got on.

What would you recommend for the rooms with the thermal skirting - if I was to put a trv in the flow pipe outside the room, should I use a thermal actuator, or would you just use another radiator controller but linked to a room stat?

How would the switch modules work? Am wondering whether I could use them for the fan convectors as well as the UFH?

And can you describe a little more how the zone valves still work in this.

Taking the downstairs system currently, there are 2 lounges and we don't tend to use them at the same time. A study which quite often does get used, a hall way, and 3 bedrooms with bathrooms, which are only really used for guests.

All this currently is controlled by a CM907 in the hallway, and TRVs on the radiators.

I understand that I could link together some of the rooms into their own zones, which could then be set up differently to other zones. But how can I get the master zone valve to work with this system - can a BDR91 be linked to control a zone valve and boiler, and then have different radiator zones interfacing with it?

Many thanks

Steve

[SensibleHeatUK]

If the valves to your skirting heating are simply in-line TRVs then I would use the Radiator Controller with a separate room sensor - this is the most cost effective way and requires no additional wiring. If the valve is a traditional zone valve then use the Switch Module with a thermal actuator instead.

If you have an Evo controller for each floor then you set up a Switch Module as a Boiler Relay, which you then wire to the main zone valve. This way any zone calling for heat will operate the zone valve, and presumably you have the end switch of the valve wired to the boiler already.

What you cannot do with Evo is have a zone that combines a BRD91 and HR80 - only one or the other can be registered to a zone. You can also register a a BRD91 as a Boiler Relay as described above. You can only register one Boiler Relay per Evo too, so that is why I suggested using one for the round floor and one for the first floor.

[vetinry]

Currently, there is a TRV built into the skirting, but it's not a standard type. So my plan was to install an inline TRV, which can then be managed by Evohome. I can then either remove the TRV on the skirting, if possible, or simply leave it wide open. Who makes a good quality inline TRV?

I think I understand - The EVO controller can only manage one boiler controller (BRD91 etc) and therefore I will require seperate controllers for different zones?

Will these talk to each other at all - one of the things I like is that these systems present an intelligent request for heat based on overall demand from zones, rather than calling independently of each other.

Does this also mean that I can simply leave the UFH zone alone because it is already wired to a seperate zone valve, which itself controls the boiler.

In your opinion, is it better to have 2 seperate zone valves for upstairs and downstairs, or would I be better to go back to a single valve, which could then control all of the heat demand?

And I'm still not absolutely sure I understand your final paragraph - sorry for being a bit slow here.

Thanks for your help

Steve

[SensibleHeatUK]

Evo controllers do not talk to each other, but as you have separate zone valves they really don't need to - the rooms on one zone valve do not need to be linked to the rooms on the other zone valve, and both zone valves can independently trigger the boiler.

My last paragraph in my last post just points out that in some cases it might be useful for a zone to control HR80s and a BRD91 together (imagine having a zone valve controlling a local zone valve where you also want to have HR80s on the radiators) but Evo will only let you register one or the other, not both on the same zone.

You can leave the UFH on its own controls if you prefer. Evo would probably give more efficient control of this zone (depending on whether the existing controls only apply basic thermostatic temperature control) but you then have the issue of managing 3 main zone valves rather than two.

If you need two Evo controllers in any case I would not swap out your zone valves and keep them inpendently controlled. If. You were to use Hometronic (where you would only have a single Boiler Relay) them you would wire both valves to the one controller rather than physically replace both valves with a single overall heating zone valve.

[vetinry]

Thanks

Think I'm getting it now.

The UFH in the kitchen is controlled by a CM907 and I'm using optimum start, which appears to be giving good consistent temperature control of the area. What would Evohome give me in that zone that I don't have?

So, if we take the current downstairs zone, I would probably like to split as follows:

Each of the 3 bedrooms and their corresponding bathrooms become a zone - so 3 zones and 6 radiator controllers.
Each lounge become a zone (there are 2 radiators in each lounge) - so 2 more zones and 4 radiator controllers.
Study to become a zone - this is going to have a fan convector and I'm not sure exactly what control I need because it may be able to be controlled by the unit itself.
Conservatory to become a zone - same solution as Study (fan convector)
Downstairs hallway and cloakroom to become a zone - 1 zone / 2 radiator controllers.

I make this 8 zones

So, do I need 1 Evohome controller, 12 radiator controllers, whatever I need to control the fan convectors, and a switch module - is this a BDR91 or something else?

Have I got this right, and what are the options for buying the radiator controllers in bulk - I see that there is a 4 pack - anything bigger than that?

Cheers

Steve

[SensibleHeatUK]

Evo and the CM907 use the same high spec control strategies (self-learning control loops with time-proportional control of the zone valve) so you would not gain anything by changing. However if you have a spare zone on Evo (if you do go for this) then you could use this in place of the CM907 but it would only be for convenience rather than adding any improved control or efficiency.

[vetinry]

I would certainly have a spare zone on the upstairs Evohome controller, but since the UFH is on a seperate zone valve, I didn't think I would be able to control it from the existing Evohome controllers?

Can you confirm that my assumptions (shopping list) for the downstairs zones makes sense and that I have understood the boiler controller properly

Thanks

Steve