Still getting condensation three weeks after PIV installed

Doubleshotdamo

We have been in our 1956 semi since 2004, and have always had condensation form on the windows.  We had cavity wall insulation fitted in 2007, and I'd say the condensation is probably worse since then.  Also, get bits of black mould in the affected rooms, not excessive, but enough.
I fitted a PIV unit in the landing ceiling, followed all the instructions etc, but three weeks on, and with the coldest night last night since I installed it, we are still getting condensation.  The landing is quite cold now (apparently, the heated versions of the PIV use more electricity and barely make a difference to the temperature of the air being blown in), and the landing window doesn't appear to get condensation now.  All doors are left partially open to allow circulation.  There are no leaking pipes, no leakage back into the loft from below, gutters are sound, extractor in the bathroom (door closed during and after use), kitchen has extractor hood (door closed and window open when cooking), so I am at a loss as to why the condensation reappears, as all the reviews I have read are glowing.

Any advice would be appreaciated.

grumbler

Doubleshotdamo said:

We had cavity wall insulation fitted in 2007, and I'd say the condensation is probably worse since then. 

That's possibly because the walls that used to attract less visible condensation in the past, got warmer.

I fitted a PIV unit in the landing ceiling, followed all the instructions etc, but three weeks on, and with the coldest night last night since I installed it, we are still getting condensation.  The landing is quite cold now (apparently, the heated versions of the PIV use more electricity and barely make a difference to the temperature of the air being blown in), and the landing window doesn't appear to get condensation now.  All doors are left partially open to allow circulation.  There are no leaking pipes, no leakage back into the loft from below, gutters are sound, extractor in the bathroom (door closed during and after use), kitchen has extractor hood (door closed and window open when cooking), so I am at a loss as to why the condensation reappears, as all the reviews I have read are glowing.

In could seasons, condensation on windows is a norm to some extent unless the air is extremely dry. Even without any other sources of humidity you, reportedly, breath out up to 2 litres of water per day. Ventilation is good, but possibly isn't powerful enough for extracting all excessive humidity. Also, 3 weeks is possibly not enough for the house inside to dry completely compared to what it was before the PIV was installed.

Ben1989

I have a PIV and it's removed condensation on all windows so something is amiss here.

I do recall it being an absolute pig to get the ducting securely over the ceiling diffuser (took me about 40 minutes). Just check this isn't loose on one side and also check the ducting on the unit itself is fully covering the outlet and check both ends of ducting is secured with jubilee/cable ties.

Have you had the PIV on full power? Mine has 5-6 power levels which you set depending on house size. Does yours have power levels? Which model do you have?

Doubleshotdamo

Ben1989 said:

I have a PIV and it's removed condensation on all windows so something is amiss here.

I do recall it being an absolute pig to get the ducting securely over the ceiling diffuser (took me about 40 minutes). Just check this isn't loose on one side and also check the ducting on the unit itself is fully covering the outlet and check both ends of ducting is secured with jubilee/cable ties.

Have you had the PIV on full power? Mine has 5-6 power levels which you set depending on house size. Does yours have power levels? Which model do you have?

Hi, I have the Nuaire Drimaster Eco HC. It's on setting 2 of 6. The ducting is secure both ends, I know what you mean, it took longer to attach the ducting than the rest of the installation! Plenty of cold air pushing out on setting 2. I blanked off one quarter as it's close to a wall, as per the manufacturer instructions. 

rob7475

How big is your house? You may need it on a higher setting than 2 in the colder months. If you put it up to 3 or 4 does it make a difference?

I think when I installed it in our house, I initially ran it on 4 for a bit before reducing to either 2 or 3.

Ben1989

That's the exact same model as mine. Mine is on maximum which I need to reduce. Here is a benchmark from Nuaire below.

"As an example a one bedroom bungalow should be set to speed 1, and a large 5 bedroom detached property would require speed 6".

I would start on maximum setting and work my way down until you start seeing condensation, and then go one level up from there. Doors being open etc won't matter, the air gets under.

Doubleshotdamo

rob7475 said:

How big is your house? You may need it on a higher setting than 2 in the colder months. If you put it up to 3 or 4 does it make a difference?

I think when I installed it in our house, I initially ran it on 4 for a bit before reducing to either 2 or 3.

Standard 3 bed semi. Speed 3 or more makes things very cold. 

Doubleshotdamo

I've now put it on setting 3. It's noticeably colder on the landing now, and I've just checked the windows and all are starting to show condensation at the bottom. I'll report back in a couple of days. 

pramsay13

We used to have very bad condensation and then installed a PIV.
In summer we have it down at 1 and then as the days get colder we put it up until it reaches 6 over the winter.
Basically if we start to get condensation in the mornings, we put it up a level. 
Even at 6 there is still a tiny bit of condensation at the bottom of the windows furthest away from the PIV, but it's a massive difference from where we were.

rob7475

Doubleshotdamo said:

I've now put it on setting 3. It's noticeably colder on the landing now, and I've just checked the windows and all are starting to show condensation at the bottom. I'll report back in a couple of days. 

You may notice it being a bit cooler directly underneath the unit. The rest of the house should be fine though.

PIV isn't a miracle fix but massively helps. We still get a little bit of condensation in the bedrooms first thing in a morning but once the doors are open to allow the PIV to circulate, it soon goes.

Things like cooking, showering, drying clothes inside etc all affect the humidity levels in the house - the higher the humidity in cooler weather, the more condensation you'll get. Do you have extractors in your kitchen and bathroom. The bathroom one should have an overrun timer or humidistat so it continues to run for a good 20 minutes after you turn the light off.

Doubleshotdamo

rob7475 said:

Doubleshotdamo said:

I've now put it on setting 3. It's noticeably colder on the landing now, and I've just checked the windows and all are starting to show condensation at the bottom. I'll report back in a couple of days. 

You may notice it being a bit cooler directly underneath the unit. The rest of the house should be fine though.

PIV isn't a miracle fix but massively helps. We still get a little bit of condensation in the bedrooms first thing in a morning but once the doors are open to allow the PIV to circulate, it soon goes.

Things like cooking, showering, drying clothes inside etc all affect the humidity levels in the house - the higher the humidity in cooler weather, the more condensation you'll get. Do you have extractors in your kitchen and bathroom. The bathroom one should have an overrun timer or humidistat so it continues to run for a good 20 minutes after you turn the light off.

Yes, extract in kitchen and bathroom. We leave the bathroom one on for at least 20 minutes after use. 
Landing is freezing now, bedroom was cold last night and this morning, all windows had condensation, daughter's room a little, our bedroom lots, downstairs lots, son's room lots. Had to go round with the window vac again. 
I really am at a loss as what to do now. Perhaps it's because the curtains are closed? I don't know