Orangery - Need some advice

Planning an orangery extension to our house. Originally thought, underfloor heating and radiator to keep it warm.. But now not sure as I have been reading things. Firstly, can I add a radiator as an extension of the house heating? (Combi Gas boiler) Can I add underfloor run as extensoin of house heating? Thanks

 

Orangery?

That's very Victorian, does Sir already possess the functions of a billiards room & an ice house?

 

Doubt it, but sirs looking for advice, not jealous sarcasm.

Yes to both, but depends on the boiler size and spare capacity, the heating controls, and pipework accessibility from the main system to the the orangery etc etc Is the orangery being used for plants, and will the heating be on for extended periods.

 

Assuming your boiler can handle the additional load, you can extend the system into an orangery.

If you want the orangery as a separate room, then you may be able to build it without building regs, but it will need to be thermally separate with external quality doors. Its best to check with the LABC, I write them an email: 'please can you confirm this orangery, which is less than 30 sq Metres, is substantially glazed and thermally separate from the house is an exempt structure.

If you extend the CH system, then you need separate controls, IE TRVs on any rads. I was told by a private inspector, this wasnt acceptable, however I managed to find a building control guidance note that stated TRVs are accepted.

If you are having a permanent opening, you dont need separate controls, although you might as well. You will then need building regs. And a SAPs test will be needed.

Unless you are on a tight budget, I would suggest having building regs anyway. That will mean foundations, floor, roof will be inspected by somebody independant from your builder. In any case, make sure the orangery has structural calculations for roof loading and lateral stability.

Bear in mind building regs gives you sone piece of mind, but may cost you more if a pedantic BC requires deep footings etc.

Wet underfloor heating, in screed system and an extra rad, is the best possible heating for an orangery. Put the pipes on the insulation, screed over. Have expansion foam around edges.

Ive built orangeries with underfloor wet systems and done correctly, they are really toasty warm. The heat is down by the floor, where you want it, whereas just rads will convect the air which will rise and get trapped high up under the lantern.

One rad as well is ideal for those unexpected cold mornings when the floor hasnt been on.

You can run underfloor heating from the boiler, but you cant just extend house system. Extending from rads nearby wont work, you need a flow and return plux control wires going back to boiler. Extending rad pipes is very limited as orangery u/floor can only be on when house system calls for heat -Im sure there are plumbers on here who understandvthat much better than me.

 

That was why I asked about the heating periods Notch. I suspected the heating periods would be different from the house, so you need to take of a separate feed and return from the boiler, and feed that to the orangery via it's own controls and blending valve. The house will be running at a flow of 80C, but the floor will be between 35 and 60C, which would be fine with a modulating boiler just working on the UFH on it's own, but no good when the main house comes on line.

But if you're recommending a radiator as well as UFH, then that's a completely different ball game, so that needs to be linked into standard house system, but possibly needs a zone valve to allow the heat through only when needed.

 

I get customers that say 'we can just extend the rad pipes from the lounge' -as youve explained, its more involved than that.

Underflow heating systems can have a mixing valve, so they take both flow and return feeds to achieve the temperature, which as you say is lower than the house rads. Because underfloor heating uses a lower temperature, I am lead to believe it only adds a small load to the heating system, which means not too much extra cost.

Underfloor heating is very efficient, provided it can use screed as a heatsink and has lots of insulation below it, 100mm minimim ideally. For best transfer from pipes to screed use a screed with an additive like retanol -faster curing, higher strength, better heat transfer (needs a screed pump for mixing).

 

If you are planning to do this as exempt work, then

"The building’s heating system must not be extended into the conservatory or porch." DCLG circular 7/13.

I don't know if this has been tested in court, as in other legislation courts have decided that the household electrical system is available as form of heating - you plug a heater in. So that would contradict the circular.

The previous situation was that the heating needed to be separate from the main house system ie able to be shut off - typically by a valve such as a TRV. So it's arguable that this will prevail.

Either way, no one checks.

 

Would this work on Dicky Davidson or Katie Price ??