PIV units

[Andy1733]

Since I've fitted solar panels and storage battery's I've been doing other things to my property to improve the efficiency
I had the old wool type insulation removed from the cavity and installed the new bead system. I've fitted smart TRV to the rads and added an additional 150mm loft insulation (250mm now).
A slight problem I'm now having is condensation. It's mainly on the windows and even opening the trickle vents are not clearing it.
So I'm left with opening windows or fitting something to remove the moisture.
I have a dehumidifier which does the job but are unsightly and are not very efficient so was wondering
Has anyone fitted a piv unit to their loft and do they work. Or is there better solutions?

 

[Murdoch]

Houses need ventilation and PIVs really only work on leaky homes

where is your condensation coming from? Drying washing?

 

[binky]

I've encountered several positive pressure fans over the years. How well they work seems to depend on the age of the property. Best results being reported from 70s/80s style properties that I've encountered.

The modern habits of basically sealing up your property isn't healthy in my opinion. I would also check your attic isn't 'sweating' . Loft insulation fitted right up to the eaves can reduce ventilation, leading to condensation in the attic. This in turn can result in damp insulation around the timbers and rotting of the wood.

 

[Andy1733]

Yeah. I know your not suppose to use rads to dry washing though 5 in a household we have around 6 loads a week and they are big loads. It's difficult to dry them other ways. Im contemplating a airer thought I think we would only get 1 load per day on it and I don't fancy washing for 6 days

I was under the impression pivs were ideal for the non felted roofs where the down a and upstairs lacked ventilation.

 

[Andy1733]

I've encountered several positive pressure fans over the years. How well they work seems to depend on the age of the property. Best results being reported from 70s/80s style properties that I've encountered.

The modern habits of basically sealing up your property isn't healthy in my opinion. I would also check your attic isn't 'sweating' . Loft insulation fitted right up to the eaves can reduce ventilation, leading to condensation in the attic. This in turn can result in damp insulation around the timbers and rotting of the wood.

Loft is fine and very dry. as I have slated roof with no felt/breathable membrane so it's very draughty tbh. When I fitted the insulation I made sure the air could still flow.
Tbh I've never had problems with damp until I had the new cavity wall insulation so it either tells you. The original (20plus years) insulation was Crap or the new stuff is too good

 

[ProDave]

Best solution by far is proper MVHR, Mechanical Ventilation with Heat Recovery, it provides fresh air in and extracts stale air, capturing most of the otherwise lost heat in a heat exchanger to warm the incoming air.

But they are seldom fitted in anything but a new house as there is a lot of work installing the ducting to all the rooms.

PIV might solve the condensation, but it will NOT make the house more efficient to heat.

 

[binky]

Drying washing that way generates lots of damp. In my house it's not a major issue, but Victorian terrace houses have lots of draughts

One thing I've seen done is to build a covered lean-to shelter on the side of the house, and fitting a washing line under it. Gets rid of the worst of the water before bringing indoors for final drying out.

 

[Murdoch]

Yeah. I know your not suppose to use rads to dry washing though 5 in a household we have around 6 loads a week and they are big loads. It's difficult to dry them other ways. Im contemplating a airer thought I think we would only get 1 load per day on it and I don't fancy washing for 6 days

I was under the impression pivs were ideal for the non felted roofs where the down a and upstairs lacked ventilation.

condensing tumble dryer or washing line are your options

you can’t dry inside and expect the water to vanish

 

[Geoff1946]

I have a dehumidifier which does the job but are unsightly and are not very efficient

Why do you consider a dehumidifier inefficient? The one I have has modest power consumption, which only contributes to warming the room air anyway. I'm told that by keeping the walls, etc reasonably dry their thermal conductivity is also kept low, helping save on heating.

 

[Andy1733]

condensing tumble dryer or washing line are your options

you can’t dry inside and expect the water to vanish

I'm not expecting it to vanish that's why I've made this post. I'm looking for solilutions

 

[Andy1733]

Why do you consider a dehumidifier inefficient? The one I have has modest power consumption, which only contributes to warming the room air anyway. I'm told that by keeping the walls, etc reasonably dry their thermal conductivity is also kept low, helping save on heating.

I consider it inefficient because the dehumidifier only works in the one room at a time or I would need multiple units running. Plus my lounge/dinning room and extension is open plan so not sure how efficient it is to clear a 40ft long room

 

[Murdoch]

I'm not expecting it to vanish that's why I've made this post. I'm looking for solilutions

condensing tumble dryer or washing line in garden ?

 

[Geoff1946]

I consider it inefficient because the dehumidifier only works in the one room at a time or I would need multiple units running. Plus my lounge/dinning room and extension is open plan so not sure how efficient it is to clear a 40ft long room

Mine runs in a conservatory which normally has the doors open onto an open plan kitchen/dining/living room bungalow. The doors to the hall and bedrooms are usually open too. When condensation starts to appear in the conservatory in autumn, that's the signal to switch on the unit. The only condensation we then see is on the bedroom windows first thing in the morning, and a little on the bathroom window after showering. Mrs occasionally puts semi dried washing in the conservatory.
I really consider a dehumidifier to be a great benefit.

 

[shaunuk]

MVHR and a condensing dryer are the way forward. If it's your long term home.
Condensation is forming on the windows because the warm humid air is meeting a cold surface, we have double glazing nearly everywhere except three small stained glass type windows which are single pane, the three single pane windows are always the ones with condensation if we are doing washing etc.
You have to bring up the temperature of those surfaces to stop condensation. MVHR would sort out the general humidity and air freshness, and a tube drier venting to the outside would deal with the water content of the washing.
If you put 5kg of washing in a washing machine and then it weighs 10kg after the wash when wet, then it has 5 litres of water that has evaporate into the home, imagine putting 5 litres of water in a bucket and throwing it at your walls and windows before going to bed every night. Thats what we are dealing with

 

[johnb2713]

MVHR and a condensing dryer are the way forward. If it's your long term home.
Condensation is forming on the windows because the warm humid air is meeting a cold surface, we have double glazing nearly everywhere except three small stained glass type windows which are single pane, the three single pane windows are always the ones with condensation if we are doing washing etc.
You have to bring up the temperature of those surfaces to stop condensation. MVHR would sort out the general humidity and air freshness, and a tube drier venting to the outside would deal with the water content of the washing.
If you put 5kg of washing in a washing machine and then it weighs 10kg after the wash when wet, then it has 5 litres of water that has evaporate into the home, imagine putting 5 litres of water in a bucket and throwing it at your walls and windows before going to bed every night. Thats what we are dealing with

We have had vented tumble driers, condensing ones and now have a heat pump one. The heat pump drier is absolutely amazing, zero condensation in the room, very little room heating from it and incredibly low consumption. Highly recommended if you need to make changes on the tumble drier front.

 

[shaunuk]

thats good to know, does it just get plumbed in for waste water ?

 

[BorisJ]

Why do you consider a dehumidifier inefficient? The one I have has modest power consumption, which only contributes to warming the room air anyway.

Electricity is an expensive way to warm room air. It is 3 1/2 times the cost of gas.

I'm told that by keeping the walls, etc reasonably dry their thermal conductivity is also kept low, helping save on heating.

 

[johnb2713]

thats good to know, does it just get plumbed in for waste water ?

Our Beko one can either pump it into a pullout drawer / tank or down a drain, the piping kit is included. I've always had Bosch white goods, this is our first step away from them and I have to say, I'm very impressed with it from all angles.

 

[binky]

The heat pump drier is absolutely amazing, zero condensation in the room, very little room heating from it and incredibly low consumption. Highly recommended if you need to make changes on the tumble drier front.

Bought one of those last year after the previous drier died. They are a little bit expensive, but I calculated it would pay for itself in 2 years in energy savings, and that was before the energy price hikes. Only thing I don't like is it tends to leave the washing ever so slightly damp sometimes, but leave the washing to air for a few hours somewhere warm, and that's sorted easily. It would probably help if I read the manual properly, there is a knack to these driers

 

[johnb2713]

Bought one of those last year after the previous drier died. They are a little bit expensive, but I calculated it would pay for itself in 2 years in energy savings, and that was before the energy price hikes. Only thing I don't like is it tends to leave the washing ever so slightly damp sometimes, but leave the washing to air for a few hours somewhere warm, and that's sorted easily. It would probably help if I read the manual properly, there is a knack to these driers

On our Beko you can trim the level of dryness from 0 to +9 with the standard being 5 i.e. in the middle. With the default it wasnt quite SWMBO's liking, a couple of steps dryer and now she's very happy. Once it's done the initial heat up it seems to drop back to about 400w, absolutely amazing compared to the 3kW pretty much constant of the old one.