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Frequently Asked Questions
1- General
Why should I consider
using underfloor heating in my new house?
Most people find radiators unsightly and intrude on interior space and design.
They always seem to be in the wrong place when it comes to furniture layout
or room design. Open design, high ceilings and windows, such as in a barn conversion,
benefit immensely from low convection and gentle radiant heat of underfloor
heating.
Is it as comfortable
as it is made out to be?
Once you experience the draught-free environment and the even temperature of
underfloor heating throughout the house you will not want to go back to traditional
heating. Low air temperature avoid drying the air as is caused by hot air from
radiators. Summer comfort is extended all year round.
Can I
have underfloor heating and radiators?
IPPEC introduced
the mixed heating system of underfloor heating on ground floor and radiators
upstairs, or in existing part of the building, as far back as 1988. Using
radiators for 2 hours in the morning and 3 hours in the evening in bedrooms,
is a cost effective solution. Towel rails in bathrooms are useful for
drying all year round. Many of IPPEC customers choose the Pexapipe radiator
system for upstairs alongside Pexatherm underfloor heating system for the ground
floor.
Can I have warm water
underfloor heating in the bathroom only?
IPPEC offers a
special radiator towel rail valve which connects PEX UFH pipe to the towel rail.
This way, low temperature water is provided from the towel rail to the floor
of the bathroom. This is an inexpensive solution for people desiring underfloor
heating in bathrooms. See the control section on this site.
What if I get a leak
in the floor?
Durable PEX pipe does not corrode or scale. It withstands high water
temperature and pressure. Should the pipe be damaged accidentally,
IPPEC supplies a repair kit which consists of PEX to PEX compression coupler
and sleeve. The circuit in question is isolated at the manifold. Pexatherm
manifolds have individual as well as overall isolation valves. The floor
is removed just in the area of the damage. The pipe is cut and reconnected
with the above kit. The floor are is remade with screed or floorboard.
What is the warranty
given on the pipe?
Reputable pipe manufacturer’s
such as ours, offer a 10 year warranty backed up by independent insurance cover
for consequential damage to property caused by leaking pipe not accidentally
damaged. Some companies offer a further 10 - 15 years warranty, but this is
only for pipe and the value of this could be as little as 1 metre of pipe with
two couplers. Therefore the insurance cover and the consequential damage are
the essence of the warranty.
What is the minimum floor
depth required?
Pexatherm UFH should be installed in a typical depth of 125 mm under floor
finishes in solid floors. The insulation over the slab is floor grade
polystyrene 50 mm thick while the screed on top is 75 mm thick. We also
supply 70 mm polystyrene floor grade insulation where floor depth allow it.
Thinner insulation can be used for larger area and on first floor or when higher
grade insulation is used such as polyurethane boards. Screed less than
60 mm thick requires reinforcement.
Pexatherm UFH can be installed between joists of suspended first floor or between
battens of floated floors. Thus the system may not require the extra depth
in floor. IPPEC supplies modules panel as well as pipe in metal
plates for such floors. See Pexatherm
systems.
Is reinforcing
mesh required?
There is no need for a mesh
if the screed is around 75 mm thick above floor insulation. A proper reinforced
mesh, i.e. not chicken wire, must be used above the pipe and in the middle of
the screed if the thickness is less than 60 mm or if there are exceptionally
high loads on the floor.
Is Pexatherm UFH expensive
to install?
Pexatherm UFH can be no more expensive than radiator central heating when
installed at 'first fix' in a new building. Laying pipe on mandatory ground
floor insulation and covering it with concrete or screed is a very cost effective
heating solution. Connecting the UFH manifold with IPPEC's primary PEX
pipe in sleeve back to boiler at first reduces installation costs further still.
Let us quote for your project and see for yourself.
Is Pexatherm UFH more
economical to run?
Yes. See Pexatherm section. This is because there is less convection and thus
lower air temperature for the same comfort level. Lower air temperature reduces
heat losses through air changes. One of the highest heat loss in space heating.
Radiators are sited under windows for better heat distribution and therefore
the heat loss through the window is quite high.
Is it true that Pexatherm
UFH is even more economical to run with condensing boilers?
Pexatherm UFH always
uses low temperature water and condensing boilers are most efficient with low
water return temperature.
Can I have UFH on both
floors.
I do not want to see radiators. You can have the PEXATHERM systems in any floor.
The pipe-in-rail or the pipe-in-staple is used in solid or suspended concrete
floor (such as beam & block), while the pipe-in-plate is used with suspended
timber or 'floated' floor. The aluminium plates with two or three grooves are
fixed to the joists and supported by insulation from below. The pipe is clipped
in the grooves and the floorboards are laid over the plates. IPPEC offers heating
panels that are fixed in floors, walls and ceilings. See the Pexatherm section
or contact us for leaflets on all these systems.
Should I use screed (or
pug) between joists or metal plates?
Metal plates diffuse the heat form pipe to floor. They are light and easy
to handle and fix. Pexatherm diffusion plates are painted black to transmit
radiant heat even when they are not 100% in contact with the floorboard. They
are available in 300, 400, and 600 mm width and are 1250 mm long.
Screed is heavy and and awkward to handle as it is a wet product. Laid in
narrow and thin strips between suspended floor joists it is liable to crack
and crumble. Specially with the pipe expanding and contracting with the heating
cycle.
Can we have wood finish
with UFH?
Yes. Any floor finish can be used with Pexatherm systems, and we are
happy to advise on laying procedure of wood floor. Our showrooms have
solid and laminate floor finishes as well as tiles and carpets in other areas.
Visit us to see the floors and feel the comfort of Pexatherm UFH systems.
I am worried about potential
problems with solid wood on heated floors.
Wood shrinks when dried by the heated floor in Winter and expand with moisture
in Summer on the unheated floor. While screed does the opposite. Float the boards
on the heated screed with a thin layer of 2-3 mm of PE foam in between. This
gives the best heat output and keep wood flat. The boards are glued together
up to 4 m width and allowed to expand at the edges under skirting boards and
into Pexatherm edge insulation and expansion joint. Trust gravity to keep it
flat on the floor.
Can I lay 2" battens
on heated screed and then fix floorboards on top?
Having a gap between heated screed and floor finish reduces UFH heat output
considerably. The air gap is an insulator and the heated air dries the wood.
Although you can bury the battens in the screed and fix the boards to them.
This option may not allow enough movement between boards and floor below. The
boards must maintaining contact with the heated screed via a plastic sheet to
avoid vapour entrapment.
I would like to use flagstone
with my underfloor heating.
Cold surfaces such as stone and tiles are ideal with Pexatherm underfloor heating.
They become pleasant to walk on in Winter. Treat them as very thick tiles. Make
sure there is enough screed on pipe before laying them and use softer screed
(mortar) in between to allow for the slight difference in expansion between
them and the screed below.
We are extending
the floor area. Which Pexatherm UFH system to use? The existing kitchen has
solid floor.
If you are willing to remove or lower the existing floor, use any of the Pexatherm
systems for solid floors. Such as pipe-in-rail or pipe-in-board. You need a
depth of about 70 mm for polystyrene (or 50 mm polyurethane) insulation plus
70 mm screed plus floor covering.
If you do not wish to remove the existing floor, then use pipe-in-plate system
throughout. This will raise your existing solid floor (and the new floor) by
at least 50 mm. The depth depends on amount of insulation required.
Can we use your
Pexatherm underfloor heating system under carpet?
Carpet and underlay are insulators and therefore resist the heat flow. The underfloor
heating has to run at slightly higher temperature under carpet than tiled floors.
Make sure you have good insulation under the carpet. See the insulation
page in the energy efficiency section. Since the main role of underlay was
to insulate the floor, then there is no need for it in a modern well insulated
house. (as floor is already insulated). Use the money saved on a better carpet.
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2- Specific to Pexatherm Underfloor Heating
How big is the manifold?
See manifold details page under Pexatherm
section.
Can you explain
why we need the manifold? What's it for and do we need a plumber to fit it?
Each room has a a heating circuit made of a long coil of pipe. All the pipes
start and return to one location and are connected to by a series of Tee fittings,
a distribution manifold, to the boiler. It is advisable to use an experienced
plumber to fit the manifold and connect it to the boiler.
Where should I place
the manifold?
Anywhere, but preferable
in a central place. That is under stairs, in an airing cupboard. IPPEC supplies
PEX primary in conduit to connect manifold to boiler in the floor and within
the floor insulation. This the best and least expensive way to connect the manifolds
that are not near the boiler. Manifolds placed centrally avoid the problem of
heat contamination when one pipe passes through another room to reach manifold.
Also pipe congestion is avoided with centrally placed manifold since pipes spread
radially from the manifold.
My boiler already
has a circulation pump. Why do I need another one for the the underfloor heating?
Underfloor heating operates at low water temperature compared to radiators.
The pump between the mixer and the manifold is required to reduce the water
temperature in the floor. This pump pulls some cool return water from the underfloor
return manifold and mixes it with a small amount of hot water from the boiler.
It then pushes mixed reduced water temperature in the floor. See the Pexatherm
control section.
Do I need a thermal store?
Not with Pexatherm UFH systems. ThePexatherm mixer valve set is used instead
saving you capital cost ane running expenses.
Do I need to put corrosion
inhibitors?
Corrosion inhibitors can
be used in PEX pipes to protect the metal parts of the systems, as in the case
of a mixed system (underfloor and radiators using the same boiler). This inhibitor
also protects the boiler, pumps and valves. Most common inhibitors can be used
with PEX pipe. Use Copal or similar with aluminium heat exchanger boilers.
Is there a need for pressure
testing before screeding?
Most suppliers recommend pressure testing before screeding. IPPEC recommends
pressure testing to 10 bar pressure and is a requirement for the warranty to
be valid. This ensures the pipe was not damaged in any way during installation
and at any stage of the construction process before screeding.
Does special screed have
to be used?
Anhydride screed (liquid
screed or self-leveling screed) can be used with Pexatherm underfloor heating
to give faster response time from a slightly thinner screed. However most underfloor
heating systems use ordinary screed with plasticiser type additive. Ready mixed
screed can be used too. The important thing to remember is that good quality
screed must be used and it must be well compacted around the pipes. IPPEC supplies
a special screed additive to use with sand and cement semidry screed.
One room is cold while
the rest of house is to temperature.
In almost all cases there is air in that room circuit. Close all other circuits
at manifold and run system until all air is vented by the automatic air vent
on the manifold. Once room is warm open other circuits.
The Pexatherm programmable
thermostat has reached temperature in the hall but other rooms are still cold.
Reduce the flow rate at manifold by closing lockshield valve half a turn until
all room reach temperature at the same time as hall.
Do we put the heating
pipes under units or cupboards?
As a general rule
we do not put PEX heating pipes under fixed cupboards or units. Sometime pipes
may be passed under cupboards leading to other areas. Those pipes can be lagged
with Pexapipe conduits to reduce the heat output if necessary.
How do we reduce the
heat output from pipes near the UFH manifold?
This is a common problems as the PEX heating pipes are close to each other near
the manifold and sometime these pipe are in the floor of an enclosed corridor.
IPPEC has been supplying, for many years, conduit pipe which when placed over
the heating pipe acts as an insulator reducing the output from the floor. The
same applies in an enclosed corridor. All the flow pipe are sheathed with the
conduit in this instance.
Can anyone lay underfloor
heating?
Laying the insulation and fixing the pipe according to the plans drawn out by
IPPEC can be done by anyone. Connecting the pipe to the manifold, pressure testing,
and connecting manifold to pump to boiler requires the service of a good plumber
or heating engineer. IPPEC can recommend installers. IPPEC has a continuous
training programme for new installers held in their training centre.
How can I be sure
that my bathroom will be warm?
We offer variable pipe spacing with a high pipe density in bathrooms to give
a high heat output.
Can I bury the electric
cables in the insulation layer under my UFH system?
There is no problem if the electric cables are in the insulation layer. However
we suggest the use the flexible Pexapipe conduit to enable replacing the cable
in the future. We also set our hot and cold plumbing pipes in conduit in the
insulation. (See the Pexapipe section.)
I will be extending
in the future. Do I need a new manifold?
We can supply primary pipe in conduit for future connection. This primary pipe
solution will cater for future extension using another manifold.
Alternatively, the UFH manifold could be placed on the common wall of extension
and existing property. Then this manifold can be extended later to connect the
second phase pipes to the enlarged manifold.
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