IanofEpping

Hi, As background we have recently completed a deep retrofit of my 1960’s family home housing three adults and three children. We added an extension, new roof and are aiming for an EnerPHit standard of thermal performance and airtightness. Measures included new triple glazing for half the windows, IWI and CWI insulation, lime parged walls, air tightness taping throughout the house, new air source heat pump and an MVHR system. A recent air tightness test has shown we have gone from a leaky 15 ACH to 5. The test was done with 14 year old double glazed PVC windows and an air conditioning unit left untaped, knowing they are a little leaky. So far so good. Three months ago, after a long wait, we switched on the MVHR system: A Zehnder Comfoair Q350 and steel ducts from 21 Degrees who also designed and commissioned the system. The commissioning process didn’t go to plan as a young engineer connected up the waste pipe to the wrong side of the machine, causing a leak a few days later. Fortunately, this was found quickly, and the waste pipe was switched over. Unfortunately, the system, hasn’t performed as well as I had hoped. I did ask 21 Degrees if it had been damaged and to their credit, they sent another engineer over who found it hadn’t. Here are the issues: The kitchen and utility rooms seem to be clear of condensation but the two bathrooms, after hot showers, remain damp after two hours and longer, so we have reverted to opening bathroom windows until the condensation has cleared. We chose not to have extraction fans fitted in these rooms, believing the MVHR extraction vents would suffice. Sadly, increasing the ventilation rate from the normal ‘2’ setting to the high ‘3’ setting makes no difference. I noticed the downstairs bathroom outlet has less suction power – perhaps a third lower than the others - unable to hold a paper tissue on the normal or high settings. I should say here, adjusting the outlet vents doesn’t make a difference. Questions 0. Are my bathroom extraction vents not working properly? 1. Should an MVHR system be able to clear bathrooms of condensation? 2. Speaking to 21 Degrees I was surprised to hear that they don’t expect the system to clear the bathroom condensation. Am I right to feel disappointed here? 3. Is it a balancing issue, whereby the supply and extraction vents need adjusting by someone, unlike me, who knows what they are doing and has the right tools? 4. You can feel the soft gentle supply of air from the supply vents but, unlike some MVHR users on this website, the circulating air flow sees lame, i.e. it doesn’t whistle under closed doors. My air supply flow can only be felt close up at the outlet ducts. Is something wrong here? I am about to lay my carpets and cut my doors to keep the recommended 10mm air gap beneath. If there any issues with the MVHR system I would obviously like to address them before this. I appreciate any thoughts and help with this. Thank you Ian

The hygrometer shows humidity at 50% by the front door. I am not sure what it was back in February. We have had a lot of wet plastering, floor screed, mist coats, and a lot of contractors in the house, so it does make sense that I need to give the house time to dry out. Thank you for all your comments.

Thank you both for your replies. It seems a shame and a bit of a design oversight that a door with such (expensive) technology to keep the home warm doesn't have a thermally broken handle. When the MVHR is working the humidity will fall, and I presume - as I have not had an MVHR before - there will be less chance the door handle will be wet when I go to open it first thing to take the dog out? However, the heat loss will remain. It's not the end of the world. I haven't removed some steel lintels over some windows - due to costs - and I suspect heat loss from them will be much greater. I see there are door handle and lock systems for passive houses*, but they are very expensive. So probably will have to compromise on what I have got. Thank you again. Ian * -

Thank you both for your replies. It seems a shame and a bit of a design oversight that a door with such (expensive) technology to keep the home warm doesn't have a thermally broken handle. When the MVHR is working the humidity will fall, and I presume - as I have not had an MVHR before - there will be less chance the door handle will be wet when I go to open it first thing to take the dog out? However, the heat loss will remain. It's not the end of the world. I haven't removed some steel lintels over some windows - due to costs - and I suspect heat loss from them will be much greater. I see there are door handle and lock systems for passive houses*, but they are very expensive. So probably will have to compromise on what I have got. Thank you again. Ian * -

In February I had some triple glazing installed as part of a retrofit project. Internorm patio doors and a new front door: KF310 UPVC/ aluminium. first thing on a cold morning I notice the internal front door handle suffers from condensation all over its surface. I highlighted this to my contractor. He returned and looked at the door and told me the installer had forgotten to install an insulation part in the handle mechanism that stops the thermal bridge. He told me he would chase this up and install the missing part. He has just got back to me to tell me the door doesn’t have a handle insulation part; unlike some other manufacturers’ doors which he thought were similar. The door he says is fine. He blames the condensation, not on the design of the door, but on high humidity in the house as I am aiming for an airtight passive house, and have yet to commission my MVHR system. However, I am running a dehumidifier and a hygrometer suggests humidity levels are fine. Has anyone experienced this with their doors? Or have a view on this? I feel a bit let down after paying a high price for doors that I thought would perform a lot better? Thank you for any thoughts.