Heating a Conservatory

[Mark]

Conservatory heater: I was thinking along the lines of a gas wall heater such as a Drugasar (only name I know for these heaters).

I've no experience of them. Would they go on a wall that is 600mm high?

mark

[David Hansen]

On Sun, 20 Jan 2008 10:11:40 -0000 someone who may be "Mark" wrote this:-

The best solution is generally a fan unit like

connected to an existing wet heating system.

These should be on a separate zone.

[geraldthehamster]

Is there any reason (apart from the usual pettifogging one) why you can't drill a couple of holes and fit a radiator?

Regards Richard

[Mark]

It would be difficult to run an extra radiator and also the the conservatory will be about 18 ft by 12 ft so would lose a lot of wall space by putting in one or maybe two big rads.

mark

[robgraham]

20 Jan, 10:11, "Mark" wrote:

What are the pro's and con's of electric U/F heating ? This would seem to be an ideal approach on a new build situation. I've got a conservatory on the drawing board - bit smaller than this one and obviously this thread is of interest.

Rob

[The Medway Handyman]

I did just this last week. After asking on this group about rad sizes & using the Myson calculator I opted for a 1200mm x 600mm double rad in a 3m x

3m x 2.4m conservatory - 1 house wall, 1 double skin wall, 2 double glazed window walls.

Way OTT. Conservatory is hot even with the TRV on its lowest setting. Customer happy however, because they leave the doors open & warm up the lounge diner.

Not a complicated job, the rad that was in the way of the new doors had been removed, but the pipes were in place. Hardest bit was drilling through the wall for the pipes.

[David Hansen]

On Sun, 20 Jan 2008 10:39:00 -0800 (PST) someone who may be robgraham wrote this:-

There are very few pros. Installation might be a trifle easier.

The cons are many. Underfloor heating reacts slowly and that is a particular problem in a room where the external gains will vary rapidly and over a large range.

Electric underfloor heating is expensive to run. There is a particular problem if it is run on off-peak electricity and the sun is unexpectedly strong.

A fan unit connected as a separate zone to existing central heating system is ideal. It can maintain a background level of warmth. It can be turned up if one decides to use the room and will then rapidly warm it up. It will react rapidly to solar changes.

[robgraham]

cottage and you will know how thick the walls are - and are usually rubble in the middle so drilling holes for pipes is a bit of a nightmare. Might have to think about microbore along the skirting.

Rob

[Andy Hall]

May well not work because you may not be able to get enough water through it.

First thing is to calculate the heat loss and size the radiators. Once you have the required heat output then you can calculate the volume of water per second that has to pass through (using the formula of mass x specific heat x temperature fall). The temperature fall will be that across the radiators (12 degrees for a conventional boiler, 20 for condensing). Using the amount of heat, you can then calculate the mass of water using its specific heat.

1 litre of water weighs approx 1kg. so you can work out the volume per second.

Then refer to the pipe tables and work on the basis of a flow velocity of no more than 1.5 metres/sec. It gets progressively harder to move water faster than this in a small tube and noisier as well.

You can download a design guide from the Copper Development Association web site

Leaflet 150. 8 and 10mm tube will not carry much heat very far, and you will probably need 4kW plus in a room of that size in your part of the country.

If you are thinking that you might use gas, then the same principle applies. Leaflet 124 is the one on that.

[Mark]

My question was about Gas wall heaters and remains unanswered....anybody?

mark

[Andrew Gabriel]

I had one before installing central heating and it was very good. Mine was 4.5kW with a thermostatic modulating burner, and kept the room temperature accurate to 0.1C (the limit of my digital thermometer) once I'd pulled the thermostat phile out and hung it under the unit. The heat exchanger is enameled steel, and does eventually corrode through (probably lasted over 20 years), although they supply spares. However, this gives a very fast heatup, unlike a Potterton one I still have with a cast iron heat exchanger which will probably last for ever, but takes quite a while before you start getting any heat from the unit.

I think you might struggle on a 600mm high wall, but give Drugasar a call.

[David Hansen]

On Sun, 20 Jan 2008 12:09:38 -0800 (PST) someone who may be robgraham wrote this:-

Drilling holes for electrical cable will also not be easy, though probably a little easier than for pipes. However, it may be possible to route either alongside the doorway, or via the roof.

[andyv]

I put a balanced flue gas wall heater in the conservatory at my last house as it was a less complex option than a radiator. The main function of the heater was to keep the room frost free at night in winter and I'd have needed a separate circuit for a radiator with a long pipe run.

The main problem I had was that the smallest gas heater I could find was still too big for the job even on the lowest setting. There were occasions when the roof vents would open at night because the room got too hot!

[Roger]

The message

from robgraham contains these words:

I have found over the years with my rubble filled stone walls that unless the wall has been repaired with cement mortar it is no great hardship to prise a few stones out of each side of the wall and build round the insertion. So far at least there have been no catastrophic collapses. :-)

[Clot]

I suspect depends upon location and intended use. I have a south facing aspect on a 25yo brick built house where I'm thinking of a 4x5m dwarf brick wall and uPVC D/G. I could extend and drill through my gas heated CH at the time of construction ( the boiler has the capacity) and I shall be putting in a power supply for standard lighting/ TV/ light power use. At present I am favouring not extending the CH and just relying upon an electric fan heater for when we will occupy the space.

[Andy Hall]

For that, when it's very cold, you may need two fan heaters of 2kW each or at a pinch a 3kW may be enough.

I would do the heat loss calculations for it, but it will be in this sort of range based on scaling from what I did.

If use will be occasional, then fan heaters are a reasonable solution. Obviously it will get expensive for long periods of use, plus there is the noise issue.

[Clot]

Thanks for the comment. I agree with both aspects. I anticipate only occasional use in evenings in early Spring / late Autumn and possibly during mid day in winter to read the newspaper at weekends! Extending the CH under the floor in essentially an "outbuilding" could be asking for fun when trying to track a problem wih the CH at a later date is my current thought!

[David Hansen]

On Wed, 23 Jan 2008 01:02:29 GMT someone who may be "Clot" wrote this:-

This may end up as a self-fulfilling prophecy. An expensive to run heating system leading to less use. Conservatories can be used for much of the year with some gentle additional heating, for everything from dining and eating to ironing.

A conservatory heater should be on a separate zone, which would make it easy. Even if it isn't on a separate zone it shouldn't add much to the difficulty of finding a problem.

Even if you don't install a wet heating system building is the ideal time to install the pipes for one. Then if you start kicking yourself after it is built installing one will be easier.

[Andy Hall]

If you are going to have to run pipes under the floor, then what you could do is to put them in during the construction but leave them unconnected. That way if you do decide to use a radiator or a fan radiator later, it won't be disruptive. Obviously if the pipes were to run on the cold side of any insulation, you would need to make sure that they were well insulated.

Are you going for a concrete floor or wood/chipboard?

- For concrete, you can use plastic pipe. John Guest and others manufacture a sleeve pipe which is larger than the water pipe. You lay this into the concrete during construction and then the water pipe is run through it. The idea is that you can insert new lengths should you ever need to (which is highly unlikely).

- For wood you can put hatches in the floor.

Either way, this is all easily done during construction, less easy afterwards.

[Clot]

Quite - I'm weighing up the pros and cons.

Agreed. this may be the option I take.