I'm considering fitting one of these. Perhaps this one:
Is there anyone with any experience of them? Are they any good? Or do
you really need to go the whole hog and spend thousands.
Looking at the prices; £400+ for the unit then all the
ducting and face plates and power, it starts adding up.
Do you need the heat exchanger? The system we have in the
extension is basically one half of the above unit - extract
only, and no 'air in' so relies on 'trickle ventilation
(fresh, not warmed air) It seems to work well and is very
quiet (I can only just hear it working if I listen carefully
in the bathroom) I'm planning in fitting another in the
The VMC units (Ventilation Mechanique Controlee ??) are
around 100euro in France. I looked at the heat exchange
version but ruled it way out ofmy budget immediately.
NOTE Email address IS correct but might not be checked for a while.
Yes, I live in Cumbria. What comes thought the trickle vents is an
icy blast - in July.
As it's a DIY jobby for me I thought I might make the ducts and
fittings. I can't see why 25mm celotex and 6mm ply can't be used to
make square-section insulated ducting, it's just a matter of the right
cross sectional area and tight joints.
The power is an issue though. Especially if it doesn't deliver the
stated thermal transfer efficiency, or it falls off rapidly as the
Yes, I do have an hayfever problem, and here in cold old Cumbria I live
in the middle of grass land! I could move to Brighton, I know.
My house is fully insulated and well sealed, so there may be some
benefits for us. One of the problems we have in equalising the
temperature though the building, only one side gets any solar gain, so
this would help that too if I make the input air come mainly into the
Yes I saw your other post after I replied. I was not aware of any room
sealed wood stoves. I think building regs require a vent on any solid
fueled stove over over 5kW, I wonder if there is an exception for room
Not that one but we have had a similar whole house ventilator for the
last 20 years and it has been very useful. The heat recovery side (in
all these units) is a bit minimal as air has low mass - so don't
expect warm air to come out of the trickle vents, it might be a few
degrees above ambient but not much else. Motor life is about 5-10
years before the bearings fail. We built it in to a new build house -
retrofitting may not be as easy as the manufacturers claim.
It certainly makes the house environment fresher and the bathrooms dry
quite quickly. If unit has a cooker extraction hood option I would
not fit that - the extractor pipe will get coated in cooking oil and
pick up dust and fluff. Simply use a normal ceiling extractor vent
somewhere convenient in the kitchen area. We mounted our motor box on
a 2 inch thick slab of rubberised horsehair on a board in the attic
and it is for all practical purposes silent.
There are no perceptible cold draught unless you sit almost
immediately under an inlet vent in a corner in which case you might
just about detect the cool air descending.
Definitely something I would fit again.
The average British house is very air leaky. The house has to be pretty
air-tight to justify a Heat Recovery and Vent system, otherwise you are
venting it twice.
Assuming your house is very well insulated and pretty well air tight. If
fitting one of these system then have a copper heater coil in the ducting
supplying heating to house. A combi can provide hot water to the coil.
This is all it may need depending on:
1. The layout of the system,
2. The insulation value
3. The air-tightness.
Then no expensive rad or UFH systems. A high flow combi can heat the copper
coil, saving space on cylinders and cost giving a simple ferrous free
system, so no sludge build ups. Using the combi makes the whole system cost
effective 0- fresh air, heat recovery and heating. Copper duct coils can be
installed at various points in the house if the insulation value is not that
great - one for downstairs, one for up. It also provides zoning, so upstairs
can be off, while downstairs is on and vice-versa. The makers usually
provide these coils or will direct you to a supplier.
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