Dear All,

Any advice or comments on the following plan?

I want to build extensions to the kitchen and dining room parts of a linked kitchen-diner. I am contemplating having under-floor heating in the new parts - a total area if around 12m2. - but not retrofitted to the existing floor. I am assuming this will remove the need for new radiators

I want to replace the floor - currently laminate on top of concrete - with tiles in the kitchen, and engineered wood in the dining room.

I am hoping to keep the existing boiler ( a 10-yr old 18kw condensing boiler). The house is a bog-standard 3-bed 60s semi with cavity wall insulation.

Any pitfalls, things to be wary of?

Thanks.

Chris

On 07/09/2013 17:18, wrote:
Dear All,

Any advice or comments on the following plan?

I want to build extensions to the kitchen and dining room parts of a linked kitchen-diner. I am contemplating having under-floor heating in the new parts - a total area if around 12m2. - but not retrofitted to the existing floor. I am assuming this will remove the need for new radiators

I want to replace the floor - currently laminate on top of concrete - with tiles in the kitchen, and engineered wood in the dining room.

I am hoping to keep the existing boiler ( a 10-yr old 18kw condensing boiler). The house is a bog-standard 3-bed 60s semi with cavity wall insulation.

Any pitfalls, things to be wary of?

Thanks.

Chris


If it's installed at build time, it'll be fine. You're wise not to try
to retro-fit it to existing floors.

You'll need a separate heating zone for the UFH and will need somewhere
to install a mixing valve (to control the UFH water temperature to a
lower lever than the rest of the system) and a dedicated pump. An
additional zone is easiest to achieve if you already have an S-Plan system.

You'll need to design the floor correctly to get the same level as the
existing floor after allowing for concrete slab, rigid foam insulation,
and screed over the UFH pipes.

You'll need to do the heat loss calculations to make sure that the UFH
will deliver sufficient heat to the new area but, since everything will
need to be built to current thermal efficiency standards, you shouldn't
have any trouble.

We converted a built-in garage into a kitchen a few years ago and
installed UFH in that in the way described above. The concrete slab was
already there and we only had about 150mm for the insulation, screed and
ceramic floor tiles - which was a bit tight, but it all works like a
dream. Because the floor is radiating, the kitchen feels comfortable at
a lower air temperature than the rest of the house.
--
Cheers,
Roger
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On Saturday, September 7, 2013 5:18:20 PM UTC+1, wrote:
Dear All,



Any advice or comments on the following plan?



I want to build extensions to the kitchen and dining room parts of a linked kitchen-diner. I am contemplating having under-floor heating in the new parts - a total area if around 12m2. - but not retrofitted to the existing floor. I am assuming this will remove the need for new radiators



I want to replace the floor - currently laminate on top of concrete - with tiles in the kitchen, and engineered wood in the dining room.



I am hoping to keep the existing boiler ( a 10-yr old 18kw condensing boiler). The house is a bog-standard 3-bed 60s semi with cavity wall insulation.

On 09/09/2013 10:07, wrote:


Roger,

Thanks for this.

Would the pump/valve be about the same size as normal pumps/valves?

The pump would be very similar to a normal CH pump, if not identical.
The UFH valve is a mechanical blending valve[1] - similar to the valves
used to feed the hot taps in sheltered accommodation, to stop people
from getting scalded. [You also need a zone valve, of course, which is
the same as your existing zone valves, assuming you've got an S-Plan
system. This needs to be controlled by a room stat located in the area
heated by the UFH.]

And where should they go ideally? Space is a bit tight in the airing cupboard, which would be my first guess, on grounds of having the pump noise away from living areas. However, the boiler will be sited in the new kitchen - very close to the UFH floors.

Chris

The pump and blending valve need to go very close to the start and end
of the UFH pipework. The zone valve needs to go at the point where your
system splits into zones - probably in the airing cupboard if that's
where the existing zone valves are. You then need a hot feed from the
zone valve down to the UFH system, and a return to the boiler.

When we did our kitchen conversion, we moved the doorway into the
kitchen and needed to brick up the old one, which was in a cavity wall.
This provided the opportunity to create a little chamber in the leaf on
the kitchen side, to accommodate the pump and valve. This has a plywood
cover which is flush with the rest of the wall, so everything is hidden.
It also happens to be right next to the boiler - so the return route
is very short. [The supply route is a lot longer because the water has
to go all the way up the airing cupboard - where the main pump and zone
valves are located, and all the way back].

[1] The principle of operation is that the water circulating round the
UFH is much cooler than that going to the radiators - typically 40
degrees rather than 75-ish. This is achieved by blending hot water from
the boiler with the cool water return from the UFH and then sending that
round. The valve is purely mechanical - like a shower mixing valve - and
thermostatically adjusts the relative proportion of new and return water
in order to achieve the desired flow temperature. The main (existing)
pump delivers hot water to the UFH zone - in the same way as it does to
the other zones - and the UFH pump simply circulated the water through
the UFH pipes.
--
Cheers,
Roger
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