Positive pressure ventilation/MVHR
Discussion
Does anyone have any recommendations for a retrofit system that will remove humid air from inside a house?
My parents are looking for a system that will primarily remove or reduce condensation from the windows. It's a 1960s house with late 90s double glazing (no trickle vents) and reasonable quality extractors in all the bathrooms. As usual a combination of cooking, showering and drying cloths indoors mean the windows are streaming in the mornings when it gets cold.
Does anyone have any recommendations for systems that can be fitted into the loft spaces upstairs and downstairs to continuously dry the air whilst recovering some heat from the expelled air?
My parents are looking for a system that will primarily remove or reduce condensation from the windows. It's a 1960s house with late 90s double glazing (no trickle vents) and reasonable quality extractors in all the bathrooms. As usual a combination of cooking, showering and drying cloths indoors mean the windows are streaming in the mornings when it gets cold.
Does anyone have any recommendations for systems that can be fitted into the loft spaces upstairs and downstairs to continuously dry the air whilst recovering some heat from the expelled air?
For a '60's house, I personally wouldn't bother with the cost and disruption of fitting MVHR; you won't have the levels of fabric insulation and airtightness to justify it. Efficiency will be impaired by air leakage elsewhere and heat recovered will be a fairly small percentage of the fabric heat loss, so payback period will be extended. If it's a 2-storey house, you need to create ducts to circulate the air from the ground floor to the heat exchanger unit in the loft, which can be difficult and disruptive to arrange discretely. Remember that MVHR is designed to run continuously at relatively low volumes, whereas your moisture generation will be intermittent and may be most effectively dealt with by shifting large volumes of air quickly, at source...
So I'd just fit decent humidistat-controlled extraction in the areas that generate the moisture, to be honest (and if they're drying clothes in the house, buy them a tumble dryer
).
If you're really set on installing MVHR, though, any of the Usual Suspects would be fine.
So I'd just fit decent humidistat-controlled extraction in the areas that generate the moisture, to be honest (and if they're drying clothes in the house, buy them a tumble dryer
).If you're really set on installing MVHR, though, any of the Usual Suspects would be fine.
Sheepshanks said:
Have you considered PIV - positive input ventilation - such as Nuaire Drimaster?
I fitted a Nuaire Drimaster Heat into a friends bungalow 2 years ago, and this has completely cured the condensation / mould issue they had in the bedrooms. Running costs are negligible. Neil - YVM said:
I fitted a Nuaire Drimaster Heat into a friends bungalow 2 years ago, and this has completely cured the condensation / mould issue they had in the bedrooms. Running costs are negligible.
Running cost of the fan is negligible but will add up if the heat option is used. You can buy it without the heater and it can be retro-fitted later if needed, although it's more expensive to do it that way.
Not too expensive, either.Muncher said:
My concern with the non heated one (and to an extent even the heated one) is that you are blowing freezing cold air from the loft down into the house, any views on that?
Most of the time the air in the loft is not freezing, and you dont notice a draft regardless. In fact a lot of the time you benefit slightly from heat recovery from the loft. The heater only comes on when the air temperature is cold.
Looks like an innovative solution to our damp problems.The input fans(PIVs) are for well sealed houses to force some air changes where virtually none would exist naturally. If a house has a chimney it will naturally vent up the chimney due to convection.
Excessive moisture is best dealt with at source. e.g. lids on pans, extractor over hob, clothes on outdoor line, extractor for showers etc.
Excessive moisture is best dealt with at source. e.g. lids on pans, extractor over hob, clothes on outdoor line, extractor for showers etc.
Today I fitted a Drimaster 2000 (it's got 2000 in the name! It can only be brilliant! Even though that was 14 years ago!) in the attic. Has an extra sensor fed through into a bedroom; when the loft is warmer than the house, it steps up the fan speed to pull the warmer air in more quickly. Wife, who has super-sensitive hearing, especially for fans, is fine with the tiny, tiny, noise on the landing (fan set to 4 out of 6) and there's no feeling of draughts at the moment.
How it does, time will tell. I've sealed a couple of major holes upstairs (one vent into a chimney, fitted a grille over the 8"x4" hole that was there and left a little bit of flow; another chimney that was open to the room and I think open to the loft space as well, although the roof goes over it since the house was extended in the sixties) to give it a chance to push the air downstairs as well.
The part that convinced me to cough up for it were the comments around the web from people who had them, weren't sure if they were doing a lot or not (most people seem to try several things, often at once)... and then they get turned off for whatever reason, and the water is back.
How it does, time will tell. I've sealed a couple of major holes upstairs (one vent into a chimney, fitted a grille over the 8"x4" hole that was there and left a little bit of flow; another chimney that was open to the room and I think open to the loft space as well, although the roof goes over it since the house was extended in the sixties) to give it a chance to push the air downstairs as well.
The part that convinced me to cough up for it were the comments around the web from people who had them, weren't sure if they were doing a lot or not (most people seem to try several things, often at once)... and then they get turned off for whatever reason, and the water is back.
Couple of weeks or so in, I can report the following:
Almost no condensation on the windows in the morning, even at sub-zero nights (previously they were like a vertical swimming pool as soon as it was "a bit nippy out"). That was improved the first morning and pretty much gone the second.
En-suite noticeably much drier (smells nicer, too). The en-suite is the far end of the house from the input vent; we run the extractor fan until about midday now instead of all day. The resulting push-pull seems to do the trick OK.
De-humidifier removed from bedroom and packed away.
A little bit cold on the landing - I've turned the fan speed down from 4 to 3. I have a feeling we might get away with 2, but so long as the moaning in the mornings has stopped, I'll leave it be To me, it feels much like there's a window open somewhere.
The thermostat is, as usual in any house with females, set stupidly high; we don't seem to be burning through oil at any great rate though so I guess it's at least balanced-ish so far as heating costs go.
The major acid test is in progress now - I wiped all the black mould (and that was looking less bad than previously) off the walls upstairs yesterday... we'll see how it all looks in a month's time!
Almost no condensation on the windows in the morning, even at sub-zero nights (previously they were like a vertical swimming pool as soon as it was "a bit nippy out"). That was improved the first morning and pretty much gone the second.
En-suite noticeably much drier (smells nicer, too). The en-suite is the far end of the house from the input vent; we run the extractor fan until about midday now instead of all day. The resulting push-pull seems to do the trick OK.
De-humidifier removed from bedroom and packed away.
A little bit cold on the landing - I've turned the fan speed down from 4 to 3. I have a feeling we might get away with 2, but so long as the moaning in the mornings has stopped, I'll leave it be
To me, it feels much like there's a window open somewhere. The thermostat is, as usual in any house with females, set stupidly high; we don't seem to be burning through oil at any great rate though so I guess it's at least balanced-ish so far as heating costs go.
The major acid test is in progress now - I wiped all the black mould (and that was looking less bad than previously) off the walls upstairs yesterday... we'll see how it all looks in a month's time!
defblade said:
Couple of weeks or so in, I can report the following:
Almost no condensation on the windows in the morning, even at sub-zero nights (previously they were like a vertical swimming pool as soon as it was "a bit nippy out"). That was improved the first morning and pretty much gone the second.
En-suite noticeably much drier (smells nicer, too). The en-suite is the far end of the house from the input vent; we run the extractor fan until about midday now instead of all day. The resulting push-pull seems to do the trick OK.
De-humidifier removed from bedroom and packed away.
A little bit cold on the landing - I've turned the fan speed down from 4 to 3. I have a feeling we might get away with 2, but so long as the moaning in the mornings has stopped, I'll leave it be To me, it feels much like there's a window open somewhere.
The thermostat is, as usual in any house with females, set stupidly high; we don't seem to be burning through oil at any great rate though so I guess it's at least balanced-ish so far as heating costs go.
The major acid test is in progress now - I wiped all the black mould (and that was looking less bad than previously) off the walls upstairs yesterday... we'll see how it all looks in a month's time!
Sounds similar to my parents experience, they bought the one with the heater in. No condensation at all, feels a little cold but they are slowly turning the fan setting down.Almost no condensation on the windows in the morning, even at sub-zero nights (previously they were like a vertical swimming pool as soon as it was "a bit nippy out"). That was improved the first morning and pretty much gone the second.
En-suite noticeably much drier (smells nicer, too). The en-suite is the far end of the house from the input vent; we run the extractor fan until about midday now instead of all day. The resulting push-pull seems to do the trick OK.
De-humidifier removed from bedroom and packed away.
A little bit cold on the landing - I've turned the fan speed down from 4 to 3. I have a feeling we might get away with 2, but so long as the moaning in the mornings has stopped, I'll leave it be
To me, it feels much like there's a window open somewhere. The thermostat is, as usual in any house with females, set stupidly high; we don't seem to be burning through oil at any great rate though so I guess it's at least balanced-ish so far as heating costs go.
The major acid test is in progress now - I wiped all the black mould (and that was looking less bad than previously) off the walls upstairs yesterday... we'll see how it all looks in a month's time!
t! Expensive to install and virtually useless when running apart from a most annoying whistling / wheezing sound that will drive you mad.Gassing Station | Homes, Gardens and DIY | Top of Page | What's New | My Stuff