Best way to install a radiator in my conservatory

[Andy]

Hi,

I am just about to buy my first house which has a currently unheated conservatory. My plan is to install a radiator into it as we plan to use it as a dinning room for the whole year.

The inside rear wall that the conservatory is "connected" too already has the main lounge raidiator on it, and it looks a fairly easy job to extend the piping from this to the new raidiator. Additionally the boiler is located in the upstairs hallway (its a combi boiler)

My question really is, is this the best way to do it ?, from reading old posts on this topic I understand the best way of installing a radiator into a conservatory is to put it onto a completly seperate "zone". To do this I presume it requires its own seperate pipes coming from the boiler which to be honest seems like it will rather expensive to do especially when there are current pipes literally the other side of the wall.

Is my current plan of simply extending the current pipes ok ? or should I really try to get the zone'ing thing done. Or is there a third method which is much better.

Also is a TRV still a satisfactory way of having the radiator controlled to ne exempt from the building regs ?

Lastly is it best to try and get the biggest raidator you can fit into the conservatory ? as there will be more heat loss than any other room, I think a reasonably powerful one will be required no ?

Thanks for advice in advance

Cheers

Andy

[Mungo]

Hi Andy, I am of no use with your predicament, but I'm in the final stages of building a conservatory on to our house. I decided to install three radiators in the four metre by four metre structure: one on the bell end and one either side of it. Each radiator is about a foot high by three foot wide (so that it fits neatly with the dwarf wall). All three supplied off a single 15mm pipe (our boiler is 40kW condensing - plenty of oomph I hope :-). All radiators have thermostatic valves on them too.

I've fitted (but not connected yet) a frost stat with the plan to allow this to kick in the heating when the conservatory temperature gets too cold. In this way I hope to avoid a burst pipe in the room.

I haven't got any experience of whether this setup will be adequate, but I'm thinking of adding a zone valve and a two-hour or four-hour timer so that we can push the button and get some heat in there when we go to use the space.

The "zoning" might not be from the boiler - depends where your other valves are?

When I tested the radiators before the floor went down (chipboard floor for me) I found that one on its own gave out a fair amount of heat. But there's no harm in trying to distribute the heat around the space instead of having one furnace at one end. I can always crank down the thermostats on the radiators if I've been over zealous!

HTH

Mungo

[mentalguy2004]

You can't wish for more than a warm bell end

Sorry, couldn't resist :)

[Andy Hall]

Mungo, did you do the heat loss calculations? Unless these are double panel radiators with fins, I think that you may find them a little short on output for this size of conservatory, and may need to supplement with additional heating when it's cold. If you do the sums, I suspect that you will find the heat loss to be in the region of 5kW at -1 degrees outside.

[Roger Mills]

You are likely to need a radiator with a fairly high heat output compared with other rooms of a similar size, because the heat loses will be much higher. Some people find that fan-assisted radiators provide a good solution for conservatories because they are fairly compact, and circulate the air much better than a pure convection radiator.

Ideally, it should be on a separate zone - with it's own timer/thermostat and zone valve. This is only really feasible if you already have an S-Plan system which lends itself to additional zones. You can't easily zone a Y-Plan system - although you *could* convert it.

If you don't want to do that, you *may* get away with connecting it to the existing pipework *providing* the pipework is of an adequate size to support the existing radiators *plus* this new biggish one and provided you won't normally want to heat the conservatory when the rest of the house isn't being heated. If you *do* go for a fan-assisted rad you probably won't need a TRV on it - just a thermostat to turn the fan on and off. It won't produce/waste very much heat when the fan isn't running. If most of the radiators in the house have TRVs and if there is a room stat to turn the lot off when up to temperature, you may need another room stat in the conservatory in parallel with the house stat. Otherwise, the house stat may turn the heating off when you still need it in the conservatory.

[Roly]

Are there any planning or building regs that need to be considered ?

The reason I ask is that I recently had to sell my mother's house and the purchaser's solicitor made a great deal of fuss to establish whether there was or wasn't a radiator in the conservatory.

As it happened, there was no radiator and they seemed perfectly happy, but I never understood what the fuss was about.

[Mungo]

[looks sheepishly towards the sky] errr no. When I specified the conservatory I said it would be heated, hence the building regulations meant that the dwarf wall cavity had to have 40mm of 'kingspan' insulation, plus the glass had to be pilkington K (or equivalent). I strapped the inside walls with 20mm wood to screw the plasterboard on to, and then I decided to fill in the gap between each straps with yet more Kingspan so there is 60mm thick insulation on the back side of each single-skin radiator.

It's my first conservatory; I should have done the calculations; at least I did put some form of heating into the area and with a muckle boiler (40kW at

91% efficiency) I hope that it works okay. There's still the wonder whether we will use the space throughout the year...

[Andy Hall]

I don't suppose that the boiler will be an issue. One thing that you could always do if you do find the heating insufficient is to add in a fan convector run from the heating circuit and use that to top up when needed. These have a lot of heat output from a small space and are a lot cheaper to run than supplementary electric heating.

[Andy Hall]

This is a Building Regulations issue.

Basically, a conservatory is considered to be outside the main insulated part of the house and one of the requirements is to have separate thermostatic controls for any radiators etc.

Generally, with a given set of criteria, conservatories are exempted from Building Regulation application and control, and this is one of the criteria.

As far as the solicitor is concerned, he probably read it in Solicitor's Weekly as part of an article on how to give clients the impression that you are on the ball while not actually having to do anything. Solicitors spend years studying this.

Although this makes sense from an energy cost and use perspective, there is little legal risk. The Building Regulations at local level are administered by the local authority. Building inspectors deal with construction projects to extensions and do a professional job that is useful in making sure that construction is safe and energy efficient. However, if somebody makes a minor contravention, they are highly unlikely to be detected and the law only allows a limited time for enforcement anyway. Presence or absence of a thermostatic radiator valve on a conservatory radiator is unlikely to spur them into making a dawn raid.

[Roly]

That's exactly the conclusion I came to. It seemed like a load of fuss for no goord reason. In that particular case, the conservatory was about

25 years old and modern building regs wouldn't have applied, but they still insisted on having all the boxes ticked.

[John Rumm]

At condensing boiler flow temperatures you will be hard pushed to get more than about 5kW delivered through a 15mm pipe anyway - so the size of the boiler is neither here nor there!

[Mungo]

Errr, thanks John... I should learn to keep my mouth shut and be thought ignorant than open it and remove all doubt!

Mungo (bows graciously out of this thread :-)

[Andy]

Sorry to sound stupid, but how do I tell if I have a S-Plan or a Y-Plan system ? What sizes pipes do you think would be adequate ?

Thanks for all the advice.

Cheers Andy

[Roger Mills]

Sorry, I just remembered that the boiler is a combi - so you probably haven't got either type of plan!

If you implement zoning, you will end up with a sort of S-Plan system - but only for the CH whereas S-Plan systems usually have a HW zone as well. You would need to split the CH output from the boiler into two circuits - with one circuit feeding the existing radiators and the other circuit serving the conservatory. You would need two 2-port valves - one in each circuit, with each valve being controlled by a separate room stat - one in the house and one in the conservatory. The boiler would then operate in CH mode whenever either (or both) zones were calling for heat - but they would effectively operate independently so that you could heat just the conservatory or just the house if you didn't want to heat both at the same time.

With regard to pipe size, as others have said, 15mm pipes connected to a boiler in condensing mode can only reasonably deliver about 5kW of heat. You may well find that you will need 5kW in the conservatory to be able to use it as a dining room in dead of winter. So if the pipes feeding the radiator on the other side of the wall are only 15mm, they clearly aren't going to have 5kW of surplus capacity - so you'll need either to increase the size or run new dedicated pipes to the conservatory. If the existing pipes are 22mm, you're probably ok - depending on what else they're feeding.

I think I would go for a separate zone if possible. There would be no argument about meeting building regs then. If you use a fan-assisted convector, and mount it high on the wall, installing pipework may not be too horrific. I think you said that the boiler was on an upstairs landing. I obviously don't know the layout of the house, but it seems possible that you might be able to bring the pipes along under the landing floor, and through the wall into the conservatory. If you use plastic pipes, it's dead easy. With a lot of solar gain and very little thermal inertia, the temperature of the converatory will drift up and down much more than that of the rest of the house, so it makes sense to have entirely separate controls for it.

[John Rumm]

Well if you knew all the answers before you started there would be little point asking the question! ;-)

Just thought I would mention that there is a limit to how much power you can shift through one pipe, and if that is already feeding a big radiator then may not be enough spare capacity for a conservatory as well. The condensing boiler may be set to run the water a bit cooler than a conventional boiler (for better efficency) so that also takes a bite out of the power available (although not that much).

[John Rumm]

By looking at the number and type of motorised valves fitted to the system, and also the number of heating pipes connected to the boiler.

See the various plans here:

> What sizes pipes do you think would be adequate ?

That depends on the size of the houe, power of the boiler, size of the rads and number, level of insulation and draft proofing etc. i.e. hard to say without knowing more. Typical installations may run "backbone" feed and return pipes in 22mm, with the individual radiators strung between these on 15mm. However there are plenty of variations possible. Big houses / high heat losses may require bigger pipe in places, and groups of smaller rads may be all run on 15mm etc.

[Andy]

Excellent thank you very much for all the info. Unfortuantly the boiler is on the upstairs landing but I forgot to mention that its on the other side of the house as well, I imagine the best way for the extra piping is right under the 2nd floor to the oposite side of the house and then down and through the main wall.

Anyway I will take a look and probably get a quote for both options, If it is not "so" expensive then I may go for the zone option, I can't wait to tell the missus we have to rip up the floor too ! But depending on current pipe size if their big enough it might just be an add on with a TRV which should be good enough for the building rgs.

Anyway thankyou for completly clearing up what needs to be done both both options.

Andy