Condensation in bedrooms. Positive Input Ventilation PIV?

Welshman said:
what sensors are they and can they be put into home assitant??
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Yes - they are what I use in HA. They report humidity, temp, their signal, and their battery state. You just need the Govee Bluetooth HA integration and it is all automatically discovered. I'd say I have some dropouts but I think that's because I am using a USB bluetooth dongle that doesn't have great coverage. If they go much further from the HA device you need an ESP32 (little mini 'puter that you can configure via HA that connects to WiFi and bridges the Bluetooth connection).
 
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dlockers said:
Yes - they are what I use in HA. They report humidity, temp, their signal, and their battery state. You just need the Govee Bluetooth module and it is all automatically discovered. I'd say I have some dropouts but I think that's because I am using a USB bluetooth dongle that doesn't have great coverage. If they go much further from the HA device you need an ESP32 (little mini 'puter that you can configure via HA that connects to WiFi and bridges the Bluetooth connection).
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Interesting, didn't know they sold a BT module and it can be used as you mentioned.
 
Vimes said:
Interesting, didn't know they sold a BT module and it can be used as you mentioned.
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Just any old USB BT adaptor. I've tried a few to gain some range but they all seem the same. The one built into the RPi3B+ (or how it communicates with HA) seemed a lot more robust; not sure what the secret is there.

Edit: sorry, get what you mean now - my words were ambiguous there - I meant install the Govee BT module in HA integration.
 
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I’ve always figured that using a dehumidifier is much better than moving warm moist air around. We had one system poorly installed that took all the warm moist air into the loft, but they’d not vented the loft properly so it literally would rain up there.
 
We've got EmonPi from OpenEnergyMonitoring installed, and they do add-on temp and humidity sensors. I'll buy a couple of these to check temps and humidity levels in bedrooms and loft before biting the bullet on installing a PIV.
 
I've got 3 dehumidifiers, that do a great job. All ~8L sized. I need multiple units as I run them at night when energy is much cheaper, and the different areas are closed off.

I have trickle vents, but that doesn't remove the moisture on wet days (which is most of them). Now, I keep the heat in and just remove all the moisture.
 
One of the very worst things anyone can do in a period property, particularly solid brick, is to insulate them either internally or externally without sufficient mitigation. I’ve seen so many examples of internal wall insulation being applied to period properties without any consideration for how it might actually affect the building - people just want to insulate insulate insulate insulate.

Period buildings literally breath and must remain porous. When people block all these routes of air flow in the name of ‘insulation’ they inevitably suffer, generate too much condensation and the building fabric decays. Sadly there are many many companies out there who couldn’t care less about this and will sell you a product that will literally damage your property.

That’s why so much effort is being put into ‘retrofit’ research that is SUITABLE- a one solution suits all approach will never work.

Passive/positive ventilation systems in the right configuration are excellent however.
 
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rangor gubbins said:
Anyone got experience with installing a PIV fan unit?
Our house is old-ish, but has been refurbed with lots of insulation and double glazing, there are no radiators and all heat is provided by underfloor heating and an ASHP. When we put the (wooden) windows in we decided not to have trickle vents. For most of the year its fine but when its very cold outside we get quite a lot of condensation on the windows and its goes mouldy.
Running the wood burning stove helps a lot, but I'd like a more constant solution to the condensation. I originally thought that we should retrofit some trickle vents. However, our house is in quite an exposed position and i think we'd get a lot of draft coming through the trickle vents.
I'm wondering if positive input ventilation would work.
It would be installed so that it will move air from our loft (which has lots of insulation in and under the rafters, so is not cold) to the main corridor on the first floor, which connects the bedrooms and bathroom. But I'm not sure whether it will reduce/stop condensation in the bedrooms if there is not much air gaps in those rooms for the fresh air to push out the humid stale air.
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PIV isn’t going to work if you have a warm loft. Also you really need some trickle vents to push the warm moist air out of.

They work by bringing in cool air. Cool air carries less moisture and lowers your relative humidity as it warms in the house. If you are pushing warm air down from the loft which is part of the same thermal envelope of the house, it’s not going to lower the humidity.

You’ve got 3 real choices:
Buy and run a dehumidifier (overnight will probably be fine)
Open your windows daily to vent the house.
Install trickle vents
Install bi-directional heat recovery extractor fans, two will probably be enough (see CharlieDYITE recent video below).

The nuclear option is to install MVHR but not a ‘real choice’ IMO as you’ll have to cut your house to pieces to install properly.

 
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dlockers said:
If it's just the lower inch or so I don't think any fix is required. It soon evaporates
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It's about that on the upper and lower panes, but the real issue is that frames are set into the outer course of bricks, and that leaves the edge of the outer bricks as the internal surface (with a bit of plaster on) inside the room. This bricke then gets quite cold overnight, and gets condesation on it.
 
@b0rn2sk8 thanks for the suggestions.
First point, while it is a warm loft, it isn't sealed to the outside and there are gaps so *I think* air would be pulled in from outside if a PIV was installed. Having said that, I do agree with you there's a risk that pushing air from the loft into the first floor won't help because most of the air in the loft has simply come from the first floor rather than the outside. We might end up just circulating air between the loft and first floor. But if there is enough gaps in the loft that we get outside air coming in, then the air we push to the
I've picked up some humidity and temp sensors, which i will put in the loft and bedrooms and compare temps and humidity for a few nights.

I'm not keen on running a dehumidifier, due to space of where to put it and cost of running. However, if we did install a PIV and it didn't work well enough I did think we could add a dehumidifier into the loft to lower the humidity of the air being push down.
We do open the windows, but this is only practical if unless one of us is working from home, I don't want to leave them open all day. Also if its raining we get rain blowing inside as the house is quite exposed to the elements.
Trickle vents. definitely something we're considering.
decentralised ventilation and heat recovery - will look into this some more. Thanks for the video.
MVHR, as you say, i don't think we can do this.
 
squerble said:
Yep, this works from a technical standpoint. If you let in outside air that is 5ºC and 90%RH, heating it up to 20ºC will reduce the relative humidity to 35%.
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Real problem the humidity will go up through the night due to condensation humans produce, it's better to keep bringing in new air, even though it means the heating needs to constantly run
 
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Firstly, try and eliminate the possible source of the problem, ease tally the humidity being created in the house.

Do you dry clothes inside, either on a clothes horse or radiators, do you use a proper extractor in the kitchen (that vents outside) and extractors in the bathrooms?

Also, how old is the house, is it solid wall (say pre-1930s) or a cavity? The wrong internal insulation inside an old house can cause no end of problems, they were not designed for it. It's really complicated and many people will get it wrong, even some soo called experts.
 
-Ad- said:
Firstly, try and eliminate the possible source of the problem, ease tally the humidity being created in the house.

Do you dry clothes inside, either on a clothes horse or radiators, do you use a proper extractor in the kitchen (that vents outside) and extractors in the bathrooms?

Also, how old is the house, is it solid wall (say pre-1930s) or a cavity? The wrong internal insulation inside an old house can cause no end of problems, they were not designed for it. It's really complicated and many people will get it wrong, even some soo called experts.
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yeah when I had people advising cavity wall insulation they said the new stuff is ok with damp conditions. yeah I call BS on that on.
 
hornetstinger said:
yeah when I had people advising cavity wall insulation they said the new stuff is ok with damp conditions. yeah I call BS on that on.
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Aye, it's a minefield. Even more sonic cavities have fill and other crap in the bottom that could cause a bridge.

It's the same for external and internal insulation companies, damn minefield. I doubt many of them even know what a condensation risk analysis model is and why it's needed.
 
-Ad- said:
Aye, it's a minefield. Even more sonic cavities have fill and other crap in the bottom that could cause a bridge.

It's the same for external and internal insulation companies, damn minefield. I doubt many of them even know what a condensation risk analysis model is and why it's needed.
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What about when they inject DPC chemical into the brick?
They also suggest to remove plaster 1m fit membrane then replaster.
 
rangor gubbins said:
@b0rn2sk8 thanks for the suggestions.
First point, while it is a warm loft, it isn't sealed to the outside and there are gaps so *I think* air would be pulled in from outside if a PIV was installed. Having said that, I do agree with you there's a risk that pushing air from the loft into the first floor won't help because most of the air in the loft has simply come from the first floor rather than the outside. We might end up just circulating air between the loft and first floor. But if there is enough gaps in the loft that we get outside air coming in, then the air we push to the
I've picked up some humidity and temp sensors, which i will put in the loft and bedrooms and compare temps and humidity for a few nights.

I'm not keen on running a dehumidifier, due to space of where to put it and cost of running. However, if we did install a PIV and it didn't work well enough I did think we could add a dehumidifier into the loft to lower the humidity of the air being push down.
We do open the windows, but this is only practical if unless one of us is working from home, I don't want to leave them open all day. Also if its raining we get rain blowing inside as the house is quite exposed to the elements.
Trickle vents. definitely something we're considering.
decentralised ventilation and heat recovery - will look into this some more. Thanks for the video.
MVHR, as you say, i don't think we can do this.
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When you say it is not sealed to the outside, what do you mean? I'd expect there to be a few small vents for trickle ventilation but that is about it.

A PIV isn't a golden ticket some people make it out to be, they work well in specific circumstances but not in others. If your house is fairly well sealed which is sounds like it will be without any trickle vents, it is not going to work well if there is nowhere for the air to go and it will be like taking a wee into the wind. Likewise, it is the same for when you are running extractors in the kitchen/bathroom, if there is nowhere for the air to enter, you'll not be extracting anything.

The windows thing was explained a few posts above, the idea isn't to open them for a long period of time, its to do it for just 3 minutes to air the house and and close them all gain.

A dehumidifier will not cost much and may not be anything more than running a PIV or fully venting the house daily. That you spend in electricity, you save a bit in heating costs from less air changes. You also wouldn't need to run it all day every day, a few hours overnight will probably be sufficient.

But fundamentally, your house sounds like it lacks a bit of ventilation, it is a requirement under building regs to have vents or mechanical ventilation across the house, that is usually in the form of trickle vents in a typical build or MVHR in a high performance build.
 
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