lizzie Posted March 10, 2019 Share Posted March 10, 2019 Me again.....I am belatedly trying to educate myself before the man comes on Tuesday and hopefully resets everything. For the sake of my sanity I need to try and understand a bit before he comes. I don't have a commissioning report the space in my book is blank. I have managed to get into the set up system via password now so can see what air flow rates I have. It gives me the rates for each level but I can't find the rates for individual rooms. These flow rates have been set, I presume, with reference to a standard starting measurement e.g building regs. They were set for the default F5 filters but I am using F7 and the handbook says there will be a pressure drop so it needs to be reset for that too. I only changed to F7 after about the first 6 months and have not noticed any difference in air pressure. My current settings and factory defaults in the handbook....see attached.. look quite different so it has been set up for my house not left at default. The attached is the comparison table I have done plus the planning drawing for the system with volumes etc plus the relevant bits from the manuals. The manual talks in volts not flow rates or air changes per hour just to confuse things even more. Can anyone help me make sense of it. mvhr parameter settings.pdf air flow details.xlsx MV36106 - MVHR Layout A2.pdf set up defaults.pdf Link to comment Share on other sites More sharing options...
Jeremy Harris Posted March 10, 2019 Share Posted March 10, 2019 The air flow rates can't be measured by the MVHR, they need to be measured using an air flow meter at every room terminal. Sadly, I suspect that many, many MVHR systems may be installed and "commissioned" without bothering to set them up properly, let's hope yours is an exception, despite the room terminal readings not having been recorded. The process is to start by setting the MVHR to the background ventilation rate (the rate it runs at most of the time) and then go around every terminal using an air flow meter to measure the flow rate either in to, or out of, the terminal, and write the reading down. Here's a photo of me measuring one of our terminals that shows how it may be done (there are different types of air flow meter): Once a set of baseline readings for every terminal have been done, the first thing is to add up the rates from all the supply terminals, then add up all the rates from the extract terminals. The total air flow for all the supply terminals must equal (more or less) the total airflow from all of the extract terminals, this ensures that the system is balanced and operating at best efficiency. If the system isn't balanced then the terminals need to be carefully adjusted to get the system in balance, or restrictor rings have to be fitted if the system uses that type of flow balancing. Once balanced, the air flows need to all be measured again and the total background ventilation rate must equal or exceed the rate given in Part F, calculated from the house area. If all's well so far, the the next stage is to increase the MVHR fan speed to boost and check the extract flow rates to ensure that the minimum room extract rates for the kitchen, bathrooms, WCs, utility room etc can be met. Those rates are in table 5.2 in Part F IIRC. The chances are that the whole house background ventilation rate may already exceed the required extract rates, in which case there's no need to do this second set of tests. When everything is completed you should have a balanced system with the measured air flow rates at every terminal listed on the commissioning report. Adjusting the whole house ventilation rate up or, most probably, down, after commissioning shouldn't upset the balance, so you can adjust things for the best comfort level without needing to go around re-doing all these measurements. The measurement process is a bit tedious and time consuming, it took me the best part of a whole day to get our system balanced and set up properly. 2 Link to comment Share on other sites More sharing options...
lizzie Posted March 10, 2019 Author Share Posted March 10, 2019 (edited) Oh wow @JSHarris I am wondering where I start! I think I need to print this out and have it as a crib sheet with the man on Tuesday. Ive just done a rough check - I have 6 in and 8 out and it seems pretty even. Thank you. Edited March 10, 2019 by lizzie Link to comment Share on other sites More sharing options...
Sue B Posted March 10, 2019 Share Posted March 10, 2019 I think you are right @JSHarris - we installed our MVHR last time but paid the supplier to come out and balance it before we used it. They were there an hour or two. They definitely didn’t have meters to check the air flow! 1 Link to comment Share on other sites More sharing options...
Jeremy Harris Posted March 10, 2019 Share Posted March 10, 2019 There are official guides as to how to do this. They vary a bit, but in essence follow much the same procedure as above: NHBC MVHR Commissioning.pdf Passivhaus MVHR Commissioning Requirements V121.pdf domestic_ventilation_compliance_guide_2010_edition.pdf Buildhub has two ventilation system air flow meters in the tool loan pool, which members can borrow to undertake testing if they wish. 3 Link to comment Share on other sites More sharing options...
joe90 Posted March 10, 2019 Share Posted March 10, 2019 3 hours ago, JSHarris said: Buildhub has two ventilation system air flow meters in the tool loan pool, which members can borrow to undertake testing if they wish. Good to know, I have to get round to balancing mine at some time. I just need to “invent” some restrictors in my home made manifold. Link to comment Share on other sites More sharing options...
lizzie Posted March 10, 2019 Author Share Posted March 10, 2019 (edited) I will report back on Tuesday...anyone have anything to add to my crib sheet from Jeremy's post please do. Edited March 10, 2019 by lizzie Link to comment Share on other sites More sharing options...
jake Posted March 10, 2019 Share Posted March 10, 2019 Super helpful guidance @JSHarris . As you say though and I fear, having worked on many low energy and passive 'principled' new builds that many mvhr systems are ill-fitted and ill-commissioned causing unnecessarily noisy, energy hungry and dust trapped ducting far from what was designed. Link to comment Share on other sites More sharing options...
Gone West Posted March 11, 2019 Share Posted March 11, 2019 @lizzie If you create a table based on the one I sent, you will be able to fill in the first four columns for your house before your technician arrives. For the first column calculate the volume of each room in cubic metres. For the second column just copy the appropriate air changes per hour rate for each room. From that for the third column you can then calculate the air flow rate per hour in cubic metres per hour. The fourth column just converts m3/h into l/s using the conversion factor of 0.277778. The last column is the calculated air flow velocity in m/s using the cross sectional area of the measuring device. Good luck . Link to comment Share on other sites More sharing options...
lizzie Posted March 11, 2019 Author Share Posted March 11, 2019 I experimented again overnight. At 4pm yesterday I turned the mvhr down to its low setting (level 2 called absent) left the monitors all running as usual. We behaved as usual, made poached eggs for supper didnt use the hob extractor. On my own in the house (with dog) until circa 9pm when OH returned. 2 of us plus pooch here from then on. I checked monitors on waking this morning at 7pm. Very little change to pre 4pm levels, humididity went from 31 to 32 and then didn't vary at all, temp stayed within a point or so of 22.9. Co2 levels increased quite a bit from hovering around 400 to nearer 500. I guess this is due to less air changes with lower mvhr rates. OH reminded me the man who originally set it used one of those trumpet like devices you hold up at the vents. That was set for F5 not F7 filters though. He did make more use of the level 2 setting on the timers though, he had it set at that level overnight, I changed it all to manual as I felt it was wrong for my breathing as set so I change it up and down myself not automatically and rarely use level 2 I tend to stick with level 3 (living), so me over ventilating is def possible. I would have thought the overnight humidity would have come up with it being at the lower level for 15 hours though. That reading of 31 is in bedroom. Living area is 29. RH is 70 at the mo. Outside humidity monitor is in a sheltered spot out of the wind. I wonder if part of it is location. We are high on a ridge and very exposed, we have lots of wind (that was a plus for me when buying the plot). Could the windy location have a drying effect on the air generally and the sheltered location of my external humdity monitor might not be giving me a true rh reading. A girl could be driven mad by all this, arts was my thing never any sciences, I once got banned from the physics lab for nearly setting the place on fire....not much change in my understanding of these things between then and now LOL Jeremy Harris I know you will despair of me! Link to comment Share on other sites More sharing options...
lizzie Posted March 11, 2019 Author Share Posted March 11, 2019 2 minutes ago, PeterStarck said: @lizzie If you create a table based on the one I sent, you will be able to fill in the first four columns for your house before your technician arrives. For the first column calculate the volume of each room in cubic metres. For the second column just copy the appropriate air changes per hour rate for each room. From that for the third column you can then calculate the air flow rate per hour in cubic metres per hour. The fourth column just converts m3/h into l/s using the conversion factor of 0.277778. The last column is the calculated air flow velocity in m/s using the cross sectional area of the measuring device. Good luck . @PeterStarck thank you for explaining that so well. I have been trying to fit mine into it but not quite getting there now I understand better will have another bash. Link to comment Share on other sites More sharing options...
Gone West Posted March 11, 2019 Share Posted March 11, 2019 5 minutes ago, lizzie said: I wonder if part of it is location. We are high on a ridge and very exposed, we have lots of wind (that was a plus for me when buying the plot). Could the windy location have a drying effect on the air generally and the sheltered location of my external humdity monitor might not be giving me a true rh reading. Where are the intake and extract vents on your house? Are they on the same wall and does that point in the direction of the prevailing wind? Are you far from the sea? Link to comment Share on other sites More sharing options...
lizzie Posted March 11, 2019 Author Share Posted March 11, 2019 5 minutes ago, PeterStarck said: Where are the intake and extract vents on your house? Are they on the same wall and does that point in the direction of the prevailing wind? Are you far from the sea? They are on the same wall about 2m apart. They are on the north wall of the house there is only about 1m between the back (north) wall of the house and the huge retaining wall we had to build....thats almost as high as the house only the top of the roof peeps over. We are single storey. Sadly I am a long way from the sea right in the middle of England so just about as far away as you can get. The wind comes in from the west over Wales hits the Malvern Hills then shoots straight up the valley (circa 30 miles) and hits us not a lot in between to slow it down but we have great views! Link to comment Share on other sites More sharing options...
Gone West Posted March 11, 2019 Share Posted March 11, 2019 2 minutes ago, lizzie said: They are on the same wall about 2m apart. They are on the north wall of the house there is only about 1m between the back (north) wall of the house and the huge retaining wall we had to build....thats almost as high as the house only the top of the roof peeps over. We are single storey. Sadly I am a long way from the sea right in the middle of England so just about as far away as you can get. The wind comes in from the west over Wales hits the Malvern Hills then shoots straight up the valley (circa 30 miles) and hits us not a lot in between to slow it down but we have great views! I can't see a real problem with that setup. 1 Link to comment Share on other sites More sharing options...
HerbJ Posted March 11, 2019 Share Posted March 11, 2019 1 hour ago, lizzie said: OH reminded me the man who originally set it used one of those trumpet like devices you hold up at the vents. That was set for F5 not F7 filters though. He did make more use of the level 2 setting on the timers though, he had it set at that level overnight, I changed it all to manual as I felt it was wrong for my breathing as set so I change it up and down myself not automatically and rarely use level 2 I tend to stick with level 3 (living), so me over ventilating is def possible. I would have thought the overnight humidity would have come up with it being at the lower level for 15 hours though. That reading of 31 is in bedroom. Living area is 29. RH is 70 at the mo. Outside humidity monitor is in a sheltered spot out of the wind. So, it seems that your original installer did commission the system using a flow meter but did not record the commissioning tests and flow values for the various settings. Is it not possible to call him and try to understand what what settings he used - BR rates = Setting? Boost Flow Rate = Setting? etc? Perhaps he did record all the settings but failed to leave you a copy? How many settings do you have? It seems strange that Setting 2 is the "absent setting" and Setting 3 "living" What is Setting 1 ( if there is such a setting)? Do you have a "Boost" setting? Link to comment Share on other sites More sharing options...
Jeremy Harris Posted March 11, 2019 Share Posted March 11, 2019 I believe the different MVHR manufacturers have different terminology for the settings. Our Genvex can have the four speed settings programmed to various percentage flow rates, with extract and supply being individually programmable. The recommended set up is for level 2 to be the normal background ventilation rate with level 3 being the normal boost rate. Level 4 is a sort of super boost (100%) and level 1 is a trickle ventilation option for when the house is unoccupied. Being able to adjust extract and supply individually is useful, as if it is hard to get the system to balance from just adjusting the terminals/restrictors in each duct, then the system can be fine tuned to fix a small imbalance, say a couple of % or so. Getting the system to balance well does mean ensuring that the design is correct, though. As extract flow rates will generally be higher than supply flow rates then it's normal to have slightly fewer extract terminals than supply terminals, for example. This also helps to keep any slight flow noise down, as this is most noticeable in rooms that would normally have supply terminals, like bedrooms and living rooms. A little bit of flow noise is often more tolerable in a kitchen or bathroom. Link to comment Share on other sites More sharing options...
HerbJ Posted March 11, 2019 Share Posted March 11, 2019 (edited) +1 to @JSHarris I've just a quick look at the info you attached earlier 20 hours ago, lizzie said: The attached is the comparison table I have done plus the planning drawing for the system with volumes etc plus the relevant bits from the manuals. The manual talks in volts not flow rates or air changes per hour just to confuse things even more. Can anyone help me make sense of it. mvhr parameter settings.pdf air flow details.xlsx MV36106 - MVHR Layout A2.pdf set up defaults.pdf So, you have 4 settings, pretty similar to that described by @JSHarris Setting 1 is your unoccupied house setting - named "moisture protect" in your details - this should be set set at 30% of BR Flow, - currently it set at 50% of Setting 3 Setting 2 is named "low" setting - this should been set at 70% of the BR Flow - currently it set at 74% of Setting 3 Setting 3 is named "living" - the BR flow rates , which I believe that was used for all the flow volumes measured - BR Flow = 100% and the subsequent setting for Setting 1, 2 and 4 - Setting 4 is your "boost " setting - this should be set at 130% of the BR Flow - currently it set at 152%% of Setting 3 All your Design info is on your layout drawing, including design flow rates for each supply and extract outlet, together with m2 area of each room ventilated. In short you have supply rate in total of ( 4x40 + 25 + 30) = 215 m3/hr extract rate in total of (4 x 20+2 x 22 + 2x45) = 212 m3/hr It seems you have been operating at Setting 3, which is the 100% BR rate and that is greatly overventilating the house. A better setting for day to day living would be Setting 2, with Setting 3 only used when you are cooking or drying clothes or having a party. Setting 4 should be used when using bathrooms etc. I don't know who created the "air flow details" spreadsheet? was this your installation/commissioning man after he commissioned the system? This requires reviewing against as some of the settings do not seem to be consistemt with the recommendations in the manual extracts you attached. Best of luck Edited March 11, 2019 by HerbJ Didn't finish Link to comment Share on other sites More sharing options...
Ed Davies Posted March 11, 2019 Share Posted March 11, 2019 It's odd that the factory default settings for levels 1, 2, and 4 don't follow the 0.3, 0.7, and 1.3 x level 3 settings guide, either. They're not bumping against the 1.8 and 10 volt limits. Link to comment Share on other sites More sharing options...
lizzie Posted March 11, 2019 Author Share Posted March 11, 2019 Thanks guys you are all so good to take so much time trying to help. @HerbJI created the air flow details spreadsheet by noting what my system is set at and then next to it the factory defaults from the manual. I have more extracts (8) than supply (6) and you all seem to have the reverse. I did a table on the passive haus numbers @PeterStarck (see attached) but it doesn't look right at all. It is way out of balance. I had to go and measure all my rooms to calculate the volume as couldn't find a plan. I think I have calculated volume correctly length x width x height but no doubt I have done something wrong to have such a result. I am so confused by the whole thing I hope the engineer will be able to make some sense of it. I realise not having the commissioning detail may be a drawback and take him more time to sort it out (I am paying engineer by the hour). I have e-mailed to asked for commissioning report but the man who did it is away this week so I wont hear back until next week. I'm sure he will give it to me if he still has it. I think I recall I was told level 3 living was the day to day level and level 2 for night time or holidays, level 4 for bathroom boost, level 1 I don't recall any mention. I've had it on level 2 all day (since yesterday afternoon ) and only used level 4 boost for bathrooms this morning and still my humidity level is very low -its 29 currently not been above 32 today and the house feels a bit stuffy. Its quieter though and I can sit at my desk without the rush of air coming over my head as usual (vent is above my desk). The dead spot in the hall is less noticeable too so reduction in the vent speed is helpful for that it seems. The system has never felt right from the start. Maybe it's me not using it properly but it just doesn't seem to work as others describe theirs. I hope the man tomorrow can sort it out, I will give him my workings and maybe he will fall about laughing LOL...better get some cake in to go with the tea he may be here a while! mvhr calcs.pdf Link to comment Share on other sites More sharing options...
Jeremy Harris Posted March 11, 2019 Share Posted March 11, 2019 @lizzie, I'm concerned that you can feel a "rush of air" as that indicates a pretty high air flow rate. When our system is running at it's normal setting, there is no sound at all in the house, and the only way to feel air movement is to stand on a chair and hold a hand over a supply terminal, when it's just possible to feel a very slight draught up close to it. Ours is set to change all the air in the house about every 2 1/4 hours, which seems fine. The air always feels fresh, smells don't seem to linger or move from one room to another (an example, I've just cooked a chicken korma in the kitchen, with no cooker hood and without boosting the MVHR and there's no smell at all outside the kitchen door). We do tend to get low relative humidity (down to maybe 30%) when it's very cold outside, which reflects the low humidity outside. I find this a bit annoying, as I've suffered from chronic rhinitis for years, which is triggered by high or low humidity (and alcohol...). We've never had the humidity in the house high enough to trigger it, but have had it low enough to do so, so I've invested in an ultrasonic humidifier for my study, which seems to work very well (when I remember to top it up). I suspect that you may be reacting to the low relative humidity rather than the air quality, as the feeling I get when the air is excessively dry is one of being bunged up. It starts as a subtle feeling that the air's a bit stuffy, then progresses to being increasing harder to breathe, enough that I become aware of the effort involved. The only drug-free fix is to spend ten minutes breathing in clean steam, which is a bit like a miracle cure for an hour or so, until the dry air brings the symptoms back. 1 Link to comment Share on other sites More sharing options...
lizzie Posted March 11, 2019 Author Share Posted March 11, 2019 @JSHarris I think there is a lot in what you say. Thank you. Link to comment Share on other sites More sharing options...
HerbJ Posted March 11, 2019 Share Posted March 11, 2019 1 hour ago, lizzie said: I did a table on the passive haus numbers @PeterStarck (see attached) but it doesn't look right at all. It is way out of balance. I had to go and measure all my rooms to calculate the volume as couldn't find a plan. I think I have calculated volume correctly length x width x height but no doubt I have done something wrong to have such a result. @lizzie No, you are on the right track . Using your layout drawing information, I calculated your floor area as 124.4 m2, so if you have high ceilings then your calculated volumes seem OK. Using my calculated floor area of 124.4 m2, the Part K minimum ventilation requirement in accordance with Table 5.1(b) - 124.4x0.3x 3.6 = 136 m3/hr, which highlights that your house has been well over-ventilated on a day to day basis at the design rates of 220 m3/hr taken from your attached documents. The reason that you have more extracts than most houses is that you have extracts in the plant room and your Master Bedroom, which were not really essential and do not need to have such high airflows in those two rooms. If you use the passivhaus/din method for sizing the airflow for normal situations then assuming 5 people living in the house gives supply airflow of 5 X 30 = 150m3/hr and using 50m3/hr for the kitchen, 30m3/hr for the bathrooms and utility and 20 m3/hr for the toilet this give s total extract rate of 160 m3/hr ( ignoring the dressing room and plant room for the moment). So, not too much out of balance. Also, all within the Part K requirements. So what I would do is to set these extract rates above for kitchen, bathrooms and toilets which all meet or exceed the minimum BR extract rates for these rooms)and use a lower rate of 10 m3/hr for the dressing room and plant room (both small rooms) = total extract rate of 180m3/hr. For the supply rates use 40m3/hr (2x20m3/hr) for the living room, 35 m3/hr for the snug and 35 m3/hr for the Master Bedroom and 30m3/hr for each of the two bedrooms = total supply rate of 170 m3/hr. Use these rates to set up the system for Setting 3, with your F7 filter in place. Then, set Settings1, 2 and 4 as detailed in your Operation Instructions. I would operate the system on Setting 2 on a day to day basis, when there are just two of you (and then dog) in occupation. It will be much quieter at all settings, more comfortable, cost less money to run and should give you everything to want..... and of course it complies with the BR. Hopefully, with your enthalpy HE , you will also see more comfortable RH% I am sure that my thoughts set out above will be picked apart by others reading it and they will identify any issues with what I have summarised. Again best of luck 1 Link to comment Share on other sites More sharing options...
Gone West Posted March 12, 2019 Share Posted March 12, 2019 13 hours ago, lizzie said: I've had it on level 2 all day (since yesterday afternoon ) and only used level 4 boost for bathrooms this morning and still my humidity level is very low -its 29 currently not been above 32 today and the house feels a bit stuffy. I don't think it is necessary to increase the ventilation level for bathroom use especially when your RH is so low. I would just leave the bathroom door open, any increase in humidity from baths or showers would be beneficial. Our system stays on level 2 all the time. As Jeremy says the system should be silent on level 2 and you should only be able to feel slight air movement next to the vent. 1 Link to comment Share on other sites More sharing options...
Gone West Posted March 12, 2019 Share Posted March 12, 2019 13 hours ago, lizzie said: I have more extracts (8) than supply (6) and you all seem to have the reverse. Not that it makes any difference now but I would have had a supply in the dressing area instead of extract and I would have had a supply in the hall as I have here. 1 Link to comment Share on other sites More sharing options...
jack Posted March 12, 2019 Share Posted March 12, 2019 1 hour ago, PeterStarck said: I don't think it is necessary to increase the ventilation level for bathroom use especially when your RH is so low. I would just leave the bathroom door open, any increase in humidity from baths or showers would be beneficial. Our system stays on level 2 all the time. Agreed. We never boost due to showers and have the system set well below BR rates, but the steam and condensation clear very quickly. I might boost for an hour if I'm cooking something smelly, but that's about it. Link to comment Share on other sites More sharing options...
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