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?
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.
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
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
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.
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.
On 20 Jan, 19:41, David Hansen
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.
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
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.
In article ,
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
I think you might struggle on a 600mm high wall, but give Drugasar
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.
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
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
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.
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.
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!
On Wed, 23 Jan 2008 01:02:29 GMT someone who may be "Clot"
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.
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.