Updating the heating system

Blinkz · 2 May 2018 at 17:45

Hey folks,

I moved house 6 months ago and now looking to update the heating system. Its currently got a fairly standard open vented system which is pretty old, heating all the radiators and the hot water. At the moment the biggest downside is that none of the radiators have a TRV on them, so its proving to be tricky to heat the house. So I'm going to be installing TRVs on all of the rads but was also wondering if it would be worth replacing them as well? They all seem like originals (late 80s house) and are all simple single chamber rads, not sure if its worth it tho? Has radiator tech improved?? I'd like to think new rads would be more efficient!

Also going to be updating the control system to one of the smart systems. I work strange hours so a learning system wouldn't be any use, as such I'm leaning towards Tado as the V3 can now do room control and the geo-fencing will be really useful as it can just heat it when I'm there. The main downside to it that I can see is that it is all mainly based in the Tado cloud, as such if I lost the internet or Tado go bust then I'll be suck with an expensive and useless system! Evohome seems to have less features but not quite as dependant on the internet or external servers!

Any suggestions or info?

bremen1874 · 2 May 2018 at 17:56

If you're fitting TRVs you won't want them on all of the radiators.

Blinkz · 2 May 2018 at 18:02

bremen1874 said:
If you're fitting TRVs you won't want them on all of the radiators.

Really? I thought the whole point of them was to be able to control the temp in individual rooms? hence needing them on all the rads? or do you mean smart rad?

bremen1874 · 2 May 2018 at 18:05

You wouldn't for example usually fit them to radiators in the room with the thermostat.

You don't want a situation where all of the radiators have shut themselves off but the thermostat is still telling the boiler that it needs to be on.

Blinkz · 2 May 2018 at 18:16

bremen1874 said:
You wouldn't for example usually fit them to radiators in the room with the thermostat.

You don't want a situation where all of the radiators have shut themselves off but the thermostat is still telling the boiler that it needs to be on.

Ah yes I see, that makes sense. Well the only room with a thermostat is the hall.

Do the smart systems with both smart thermostat and smart rad trvs take that into account? (Ie if no rads are asking for heat it will switch off the boiler?)

bremen1874 · 2 May 2018 at 18:28

I don't know.

Smart TRVs would have to become a lot cheaper before I'd bother with them so I haven't investigated.

My TRVs are set to a level that works and are basically never touched. I don't feel the need for any additional control and the payback time on any potential fuel savings would be stupidly long.

Firestar_3x · 2 May 2018 at 19:31

My system (Drayton Wiser) know what devices and in each room and therefore a thermostat will not fight against a TRV, or two TRV's will not fight against each other.

samcat · 3 May 2018 at 09:35

Blinkz said:
Ah yes I see, that makes sense. Well the only room with a thermostat is the hall.

Do the smart systems with both smart thermostat and smart rad trvs take that into account? (Ie if no rads are asking for heat it will switch off the boiler?)

My bro has start TRVs in some rooms (kids bedrooms). You set a temperature schedule (so this time of day I want this room no colder than X) and if it drops below it turns the heating on and runs till the temp is over threshold.

Thermostat in hall is usually the best spot as it tends to be the coolest place in the house, so by the time the hall is up to temperature every room will be at a comfortable temperature. We put ours in the living room originally, but between family being in there, technology being on etc the thermostat would decide the room was up to temperature (which it was), but the rest of the house would be too cold. Moved it to hall, no problem since.

No TRVs on the rad(s) in the hall/open plan room with the thermostat. TRVs on every other room except bathroom(s) - helps to dry them out if whenever the heating is on they are heated.

To set it up: in winter/cold day turn all the TRVs down to a low temperature. dial thermostat up quite high and gradually adjust each main room thats used/lived in until happy. This gives a good starting point.
Empty/unused rooms will probably be happy on the low temperature originally set. They need a bit of warmth but not too much.
Over the course of the start of the winter adjust the TRVs to a comfortable temperature in each room a little at a time. The temptation when cold is to whack it up to max, try not to do that, just adjust it a little bit.

One you have a comfortable setting for each room note the settings down somewhere that you wont lose.

That's what we did and its mostly right!

wendyLG · 3 May 2018 at 10:47

Renewing the rads would be a good idea, as I have been told they fill up with silt so become less efficient, and yes modern rads do pump out more heat with all the little fins etc.

Salty22 · 7 May 2018 at 11:12

I replaced the rads in my bedroom, sons room, fitted a new one in my extension utility room and changed an old rad for the biggest size towel rack in the bathroom.
Massive difference in heat output from the new ones in my opinion, I’ve still got two double ones in my living room, hallway and daughters room so planning to change those out soon.

Pocah · 7 May 2018 at 14:45

Built in the 80's you could have a number of different boiler control plans and it really depends on which you already have as to what you should do about it. That may require new multi-way valves and controllers/thermostats.
Not all boilers can be updated either, so you first have to find out which plan you are using, which you would like to use, and check to see if you can use it with your boiler.
Regards controllers the key element here is when the boiler turns on to achieve the required room temperatures. Turns on too early and it hits the room temperature too early and so is wasting a lot of heat keeping it at that temperature when no one is home. Turns on too late and the house is cold when you get home. There are many algorithms that attempt to do this but the best are learning algorithms. Basically they learn how your house and central heating system work together under different circumstances and they control your boiler accordingly to try to turn on at the right time to hit the target temperature just as you arrive home. But again there factors here and huge amounts of research goes in to those algorithms.
There are plenty of thermostatic valves but honestly I never really found them to be that good. Rather it proved enough to have a few zones in the house and just have a thermostat in each zone, using the controller to sort out the mess. It very much depends on the layout of the house and whether people shut doors and so on. If people shut doors all the time then TRV's come in to their own.
Fitting TRV's many plumbers often omit then in the same room as the thermostat. This is for several reasons. Firstly, it would be kinda silly to fit them in the same room as the thermostat but secondly it is to protect the boiler. Without knowing what type of boiler you have it is always best to leave at least one radiator without a TRV. This is so there is always SOME flow in the system. Many modern boilers are just fine but many the same ages as yours that used 8mm and 10mm piping were not.
Honestly I think you could do better with your money investing in controls rather than new radiators.

Blinkz · 10 May 2018 at 22:22

Thanks for all of your input, it’s very much appreciated.

Glad to hear that new rads will be more efficient and quicker to heat, altho the rads we currently have do have a few metal fins at the back of them?

The system as a whole is fairly basic as I said. Standard open vented, it does have micro bore pipes to the radiators. Not sure what you mean by upgrading controls? I’m going to get the Tado smart stat for it as well as add trvs to all of the new rads. In fact I was going to just add the trvs to the rads to be able to get some control of it as at the moment it’s ether all on or all off! But whilst adding trvs it didn’t seem a bad idea to get modern rads at the same time. I don’t know what more control I could add to it? I don’t believe there is any simple option to split it into multiple zones, other then use smart rad stats?

Pocah · 13 May 2018 at 11:57

By controls really I mean anything that controls the boiler. So first question would be, can you independently control hot water for baths and the central heating. Many control systems in the 80's could not. You can look up control plans on the internet and find out which yours is and see all the others. There is gravity, C, W, Y and S.
You could not have the central heating on without it trying to heat the water at the same time. They often didn't have tank stats either. So ( and this is just an example ) one of the first upgrades to an 80's boiler is often to replace the central heating controller with one that can independently control water and central heating. So that's upgrading a gravity to a C plan.
It may sound complicated but all the plans are well documented and you just need to follow the instructions for particular the controller you buy. Each controller has precise installer instructions for all the plans. Most manufacturers make all the bits you need too and you can often buy them all in one as a kit.You also need to check that the boiler can do the plan you want. Most 80's boilers can but you have to check.
Anyway, if you think that is too complex, micro-bore, yes, you should not put TRV's on the radiators in the room in which the thermostat is in. This is to ensure that there is always an open loop in the heating system so that hot water from the boiler can flow somewhere.
Radiators are important but having said that they only affect the rate at which heat is transferred in to the room. Modern radiators are better at transferring heat faster but they are not more efficient. Usually it's only a good idea to replace them if there is a problem with the system. Like the house never reaches it's target temperature or takes too long to do so. In which case it could be the radiators or it could be the boiler.