Heating Design

[diy_darren]

As the weather starts to warm I'll be removing my existing heating system (old gas boiler, single rads) and replacing it with a combi boilder - most likely Vaillant 837.

I'm trying to design a flexible and economical system and wondered if what I'm planning is achievable and worth the effort.

I want to break the house up into zones, 7 in total, so I can control the temperatures in various rooms. Various bedrooms are unused, so providing them less heat seems logical. I'd also like to alter the temperature based on time of day. For instance, the main bedroom only really needs full temperature in the morning and last thing at night, so early evening it could be set lower.

I understand how each zone valve is linked to an individual thermostat, but don't fully understand what gizmo I need to wire all these into so the boiler only fires when needed.

 

[D_Hailsham]

Various bedrooms are unused, so providing them less heat seems logical.

Put TRVs on the rads in these bedrooms, set them to 2 and shut the door

The main bedroom only really needs full temperature in the morning and last thing at night, so early evening it could be set lower.

Bedrooms should only be at about 17-18C. I would have thought you could achieve what you want with a TRV.

I'd also like to alter the temperature based on time of day. I understand how each zone valve is linked to an individual thermostat, but don't fully understand what gizmo I need to wire all these into so the boiler only fires when needed.

You will need a wireless system such as the Honeywell CM Zone. This only has four zones, but that should be sufficient if you use TRVs as well.

Most installations only have two or three zones, so seven seems a bit excessive. It might help if you gave an indication of the size of your house: how many floors, bedrooms living rooms etc.

 

[diy_darren]

This house isn't huge, 2 floors, 4 bedrooms, upstairs bathroom, downstairs WC and open plan kitchen/diner/living space.

TRVs would give most of what I need, but they still require altering each day morning and night, which would soon start to become a chore. I'm not a great fan of TRVs, perhaps my experience of less expensive models. They tend to clog up, don't offer very even control over their range and when set to 0 don't always shut off the valve completely to remove the radiator.

I guess I'm barking up the home automation route rather than your off the shelf heating controls.

 

[gas4you]

If you don't like/want standard TRV's, then look at the Honeywell Hometronic system (think it's called that )

Basically electronic trv's, wirelessly linked back to central control unit.

 

[Agile]

How many people live there?

Why do you need any room to be other than on or off?

Tony

 

[lagunaglen]

Which trv`s will you be altering morning and night ? Your room stat will logically be in the open plan area as this will get cooler quicker than other rooms,and i have never had to alter my bedroom trv`s other than once in summer and again in winter.Think you may be trying to over complicate things or are a bit too much into gadgets.

 

[stem]

I installed a system for my parents in their bungalow 25 years ago. It comprises 7 room thermostats linked to 7 motorised valves controlling the temperature in each room. these were wired to two time switches to allow different rooms to be on at different times. (ie bathroom & bedrooms on earlier, lounge not on at all on weekday mornings when everyone was going out to work) As the motorised valves are fitted with micro switches, when all of the rooms reach temperature, the system shuts down.

It works well, and is useful, for example, in the autumn a simple flick of a switch and just the bathroom radiator comes on at a higher temperature.

In very cold weather the bedrooms only can remain on low all night, and in the morning the rest of the heating comes on.

You can now get programmable thermostats that would allow you to set different temperatures for diferent times of the day.

Having said all of that........

In hindsight I wouldn't do it again. It didn't seem to make any saving on gas and it's become a bit of a maintenance headache. Every year at least one valve and or thermostat fails, several valves have leaked, and when BG installed a new combi it took them forever to work out how to wire it even with the wiring diagrams I'd left.

Stick with TRV's.

 

[Agile]

By now your parents have probably retired and may well have become set in their ways and do the same things every dat at the same time.

Apart from teachers, few people have such a stable timetable every day.

I still find most people still prefer a dial thermostat they can manually adjust.

There are some modern digi stats which have a simple on/off button which some tenants I know find easy to use.

Tony

 

[D_Hailsham]

This house isn't huge, 2 floors, 4 bedrooms, upstairs bathroom, downstairs WC and open plan kitchen/diner/living space.

I still can't see why you would need seven zones

Here is what I would do:

Zone 1: Ground Floor - There is no sense in trying to have different temperatures in each area downstairs so put the programmer( e.g CM927) in the living area with TRVs on all rads, except one, and on the rad in downstairs WC.

Zone 2: First floor - put a zone valve to control the whole floor with the Programmer (CM927) in the main bedroom. TRVs on all rads in the other rooms, set low if the room is unused.

When the programmer turns the boiler on, it will call for heat until the programmer temperature is reached, say 21C. If a TRV is set to a lower temperature,say 18C, the TRV will shut the rad down. But if the programmer is then changed to,say 15C, the boiler will turn off at 15C and the bedroom with the 18C TRV will probably only reach 15C. It will not be 100% accurate as the temperature reached will depend on how accurately the radiator has been sized for the heat loss.

If you don't like/want standard TRV's, then look at the Honeywell Hometronic system (think it's called that )

Basically electronic trv's, wirelessly linked back to central control unit.

The Honeywell CM Zone does the same without the bells and whistles to turn on the lights or open the awning over your patio etc etc.

Have a look at CM Zone

The only problem, so far as not meeting the OP's requirements, is that both Hometronic and CM Zone use thermostatic radiators and there would still be the need to go round and adjust them each day.

If this requirement is essential, and I doubt it, the only solution is to have a zone valve attached to each adjustable radiator with an associated programmer, say the Honeywell wireless CM927, which allows 6 separate time/temperature settings every day of the week.

I'm not a great fan of TRVs, perhaps my experience of less expensive models. They tend to clog up, don't offer very even control over their range and when set to 0 don't always shut off the valve completely to remove the radiator.

There is no point in buying cheap TRVs! Drayton, HOneywell or Danfoss are reliable.

Control is down to balancing, which is even more essential when TRVs are used. Read Balancing TRVs

Although some TRVs do not have an OFF position, the better ones provide a "decorators cap", which screws on instead of the thermostatic head, to shut the valve down for rad removal.

 

[tabs]

As has been said by others there really is no need to over complicate your system as it will lead to extra cost in materials and upkeep and little to no saving in fuel.

How ever if you must do it you can actually get a manifold that can be wired up to close individual circuits, and microstats in each room either wired or wireless that provide control. This sort of stuff is not DIY and very few installers do it, you're basically going down the home auto route here as if you go for wireless microstats there is no off the shelf solution and various interfaces and programming will be involved.

 

[diy_darren]

Thanks for the replies so far as I'm not fully decided on the system, so new/different viewpoints are good.

I still favour the idea of being able to control temperatures on a room by room basis (7 zones for 7 individual spaces in the house). I also like the idea of being able to alter the temperature in a room throughout the day, independently of other rooms, by some automated means (i.e. bathroom 22 degrees from 6am - 8am, then down to 18 degrees from 6pm - 11pm).

stem, I'd like to understand how you controlled the system you installed for your parents? Also, how did you calculate energy savings to determine there weren't any?

I know I don't want a system that uses wireless components. Having to put batteries in things just seems like a step backwards imo. I know I could use decent quality TRVs to give me most of what I'm looking for, but I'm not ready to settle for that just yet. I'm concerned with the reliability of my proposed system, especially with stem's experience of something needing replacing each year. Is it unreasonable to ask a component costing £50, who's only job is to open/close to last for 10 years or more? Is it the motors on zone valves which give up as scale builds up on the internal components?

Microstat, digistat, manifold, I'm not completely sure what all these terms mean :/

I'll do some more research into the home automation offerings, but last time I looked I thought it was too pricey for what it offered. I best hurry up though as the new services room is built and floorboard lifting will be starting soon!

 

[LUNAT]

HI

7 thermostats,7 zone valves =£400.
more components more expense.even after all this it will not reduce the gas bill that much.having the rads on minimum is better that turning off (damp etc).i would sick to simplicity.

 

[gavinda]

dude, you are seriously overegging the pudding here. you do not need that amount of control. for all the points mentioned. remember

Keep
It
Simple
Stupid.

1 boiler 1 digistat 7 trv's
cheap. easy. cheap.


plus when it all goes wrong, do you really wanna be paying someone to sort out your overcomplicated mess.

best of luck.

 

[simond]

D_Hailsham wrote

[/quote]The only problem, so far as not meeting the OP's requirements, is that both Hometronic and CM Zone use thermostatic radiators and there would still be the need to go round and adjust them each day.[/quote]

Actually, nothing could be further from the truth. Hometronic (and in a limited way, its poor relation, CM Zone) can deliver up to 1600 heating setpoints a week.

Each zone is temperature monitored by the TRV head.

This stuff is the future, now. Forget pipes and motorised valves and thermostats, the HR80UK radiator head is all this in one simple unit. You just add a Hometronic Manager and you have a whole house BMS. It is the pinnacle in home energy conservation & management for the larger property.

In my opinion.

 

[D_Hailsham]

D_Hailsham wrote

The only problem, so far as not meeting the OP's requirements, is that both Hometronic and CM Zone use thermostatic radiators and there would still be the need to go round and adjust them each day.

Actually, nothing could be further from the truth. Hometronic (and in a limited way, its poor relation, CM Zone) can deliver up to 1600 heating setpoints a week.

Each zone is temperature monitored by the TRV head.

Agreed but the OP wants to control the temperatures of individual radiators. Hometronic and CM Zone work on the basis of multiple radiators in a zone, all set to the same temperature; you cannot control individual radiators within a zone

To meet the OPs requirements, each radiator would have to be in its own zone with several controllers, depending on how many zones a controller can handle.