Triassic Posted January 20, 2020 Author Share Posted January 20, 2020 Looking through a couple of the quotes, both suggest using a pair of 63mm ducts where the single duct airflow is too high. I assume this is the approach others on here us? In my case Smaller diameter ducts would be easier to run. Could I terminate these in separate outlets (in the same room) rather than one single outlet? Link to comment Share on other sites More sharing options...
JFDIY Posted January 20, 2020 Share Posted January 20, 2020 39 minutes ago, Triassic said: Could I terminate these in separate outlets (in the same room) rather than one single outlet? Yes, you just need the total flow to be correct, doesn't matter if you one or ten outlets from a compliance point of view. Link to comment Share on other sites More sharing options...
Triassic Posted January 20, 2020 Author Share Posted January 20, 2020 Looking next at the boost function. Some mention having a button to press, for others the boost comes on when the light in the bathroom is switched on, others us a RH sensor. Which is best practice, simplest method (foolproof!) cheapest? Link to comment Share on other sites More sharing options...
MJNewton Posted January 20, 2020 Share Posted January 20, 2020 (edited) For ours the RH sensor works extremely well for showers, baths, some cooking (boiling) and drying clothes... However, it's obviously no good for cooking smells so for that we've got a boost button next to the hob. Similarly, we have boost buttona outside the bathrooms but tend to rarely use them. The boost buttons are actually wired as inputs to a smart relay which, in turn, triggers the boost function as eventually once I get more time (yeah right!) I'd like to experiment more with home automation, voice control etc for various things which may or may not include the ventilation system. Edited January 20, 2020 by MJNewton Link to comment Share on other sites More sharing options...
joth Posted January 20, 2020 Share Posted January 20, 2020 (edited) 1 hour ago, MJNewton said: The boost buttons are actually wired as inputs to a smart relay which, in turn, triggers the boost function as eventually once I get more time (yeah right!) I'd like to experiment more with home automation, voice control etc for various things which may or may not include the ventilation system. Yeah on this line my current thought here is to put energy meter on the hob & oven, and just have the HA crank up the boost when they go above a certain threshold. Originally I was going to try and hook it into the hob extractor fan, but this seems simpler and might even reduce the need to run the extractor. Same for the washing machine? Coffee machine and bread maker could also be monitored with a negating effect, to keep those smells around longer :-D Edited January 20, 2020 by joth Link to comment Share on other sites More sharing options...
Triassic Posted January 20, 2020 Author Share Posted January 20, 2020 Thanks for the replies regarding the boost options. I have a vaulted ceiling in the kitchen family room. I was thinking of positioning the inlet and extract vents at around 2m above the floor. I was thinking that I could have the extract rate slightly higher than the input rate, in that way the air flow would be from the family side of the room to the kitchen extract. Is 2m too high given that the peak of the vaulted ceiling is around 4 m tall? Link to comment Share on other sites More sharing options...
MJNewton Posted January 20, 2020 Share Posted January 20, 2020 (edited) 24 minutes ago, joth said: Yeah on this line my current thought here is to put energy meter on the hob & oven, and just have the HA crank up the boost when they go above a certain threshold. Yes, I was thinking about similar. Did you have a particular plan in mind? I assumed that a non-contact current transformer wrapped around the live feed would be the best sensor but wasn't sure on the best/safest place to do this given that the cores are only separated at each end where there's not much room to fit anything else like this? That said, I was assuming it'd be done at the hob/oven end but maybe inside the consumer unit would actually be the easiest place to do it? Edited January 20, 2020 by MJNewton Link to comment Share on other sites More sharing options...
joth Posted January 21, 2020 Share Posted January 21, 2020 (edited) 8 hours ago, MJNewton said: That said, I was assuming it'd be done at the hob/oven end but maybe inside the consumer unit would actually be the easiest place to do it? With I double decker CU I should be able to put an Eastron SDM120CT on each circuit of interest. They're going for about £22 on AliExpress and reasonable examples of using them around. Definitely want the CT rather than direct connect version, to keep it non-intrusive in the circuit commissioning. There's also the very cheap alternative PZEM-016, but looks messy to put in a CU Edited January 21, 2020 by joth Link to comment Share on other sites More sharing options...
HerbJ Posted January 21, 2020 Share Posted January 21, 2020 The MVHR is automatically boosted when the light is turned on ( via a auxiliary relay,, and runs for 15 minutes after the light is turned off, in each of the downstairs WC, the bathrooms ( family and ensuites). Our MVHR system has a remote control panel ( which allows us to control all the MVHR settings), which is installed in the hall, close to the kitchen and utility room. So for us, it is a simple matter to manually switch the MVHR to boost when required when coking or drying clothes in the utility room. Link to comment Share on other sites More sharing options...
Triassic Posted January 21, 2020 Author Share Posted January 21, 2020 1 hour ago, HerbJ said: Our MVHR system has a remote control panel How is this connected WIFI or hard wired? If hard wired, how many core cable size Link to comment Share on other sites More sharing options...
HerbJ Posted January 21, 2020 Share Posted January 21, 2020 7 hours ago, Triassic said: How is this connected WIFI or hard wired? If hard wired, how many core cable size It's a propriety system supplied with the MVHR system by PAUL. In fact, there is no control panel on the MVHR Unit. The touch screen control panel is directly connected to the MVHR by Cat6 cable and there is a special connector at the unit. From memory, there are only 3 cores of the CAT6 cable used. There is no connection to the internet for my model, but I believe that this may now be an option. https://www.paulheatrecovery.co.uk/product/paul-tft-touch-screen/ Link to comment Share on other sites More sharing options...
Triassic Posted January 25, 2020 Author Share Posted January 25, 2020 (edited) I’m starting to look at prices and placing orders. Ive found plenum are £5 each suitable for 75mm duct pipe. This set me to wondering, are the plenum from different manufacturers all made to the same standard size and conversely, is 75mm ducting from different manufacturers/ suppliers all the same size? I would hate to buy plenum from one firm and find they aren’t compatible with another’s pipe. Edited January 25, 2020 by Triassic Link to comment Share on other sites More sharing options...
Triassic Posted January 25, 2020 Author Share Posted January 25, 2020 . Link to comment Share on other sites More sharing options...
Oz07 Posted January 25, 2020 Share Posted January 25, 2020 Im tight myself but being new to this system I just went with a one stop shop and accepted that I probably overpaid a little. I'm happy to start shopping around once I grasp a subject but just wanted this to be all supplied by one firm. My 2 pence! Link to comment Share on other sites More sharing options...
Triassic Posted January 26, 2020 Author Share Posted January 26, 2020 @Oz07 I get your point. I’m thinking I’ll go with BOC Ventilation, as they appear to be well thought of on here. Link to comment Share on other sites More sharing options...
Oz07 Posted January 26, 2020 Share Posted January 26, 2020 That's what I did. Im not sure their sales dept is that knowledgeable but you can discuss with the technical side. Link to comment Share on other sites More sharing options...
Triassic Posted January 29, 2020 Author Share Posted January 29, 2020 I've finally completed my MVHR design ! All I need to do now is buy a MVHR unit. Any suggestions regarding make? I'm after a unit sized around 410m3/h. Ive looked at VentAxia and Domus so far, any other suggestions? Link to comment Share on other sites More sharing options...
Nickfromwales Posted January 29, 2020 Share Posted January 29, 2020 2 hours ago, Triassic said: I've finally completed my MVHR design ! All I need to do now is buy a MVHR unit. Any suggestions regarding make? I'm after a unit sized around 410m3/h. Ive looked at VentAxia and Domus so far, any other suggestions? Give Nick Vaisey a ring at CVC Ventilation and grab a Brink unit. PH certified on VW prices Link to comment Share on other sites More sharing options...
AliG Posted February 3, 2020 Share Posted February 3, 2020 My house is around 900m2 and the volume the MVHR is used in is around 2300m3. We have quite a few double height areas, but we also have a pool room with its own system. I note that the Scottish regs say to not include volume in a room above 3m in height, but if this is open to another floor then it would be included in the area of that floor. The heating engineers specified three MVHR units. We have 2x Dantherm HCH5 and 1x HCV5.These have a max airflow of 375M3/hour each. I do not have the calculations for the sizing of my system, but it seems to me that systems are being oversized due to the regulations. The buildings regs are often on a worst case assumption. They don't know how many people will be in your house, how often you will shower, will you be hanging stuff to dry on radiators etc. As many people on here are building quite spacious houses, the minimum ventilation requirements are likely to be way more than is needed. The amount of CO2 and RH in the house is mainly driven by the activity of the people in the house, not the size. Indeed as the house gets larger, the people will have less effect in it. Thus I suspect that when people feel they have an over specified system it may just be following the regs. When our system was installed it was set to auto which bumped up the speed, when RH got above 45%. I increased this number as I found that it left the system running on speed 2 or 3 a lot of the time. I also noticed that simply it being wet outside was enough to push the RH above the boost trigger point. The average RH in Edinburgh is 80%(I assume it is boosted by the amount of rain). At first I tried increasing the RH boost point to 50%, but again I found that we were sitting at just above 50% a lot of the time. Having monitored the system over a year I decided that I couldn't really tell the difference between 45 and 55% RH so, I decided to switch off the auto boost function. Instead I switched the units to a time of day programme where they run at speed 2 in the morning and just before bed when people are likely to take a shower and speed 1 the rest of the time. I cannot find any ill effects from this and it has materially cut the heating bill. I had changed 2 of the 3 units and one was still running faster. I noticed that rooms connected to it cooled down much more during cold nights as even with heat recovery you are bringing colder outside air into the house. I don't know if anyone else has noticed this effect, where running the MVHR too hard boosts heating costs? Link to comment Share on other sites More sharing options...
Triassic Posted February 6, 2020 Author Share Posted February 6, 2020 Im about to order the ducting and have been offered anti bacterial and anti static ducting at £145 a 50m roll. I see they have standard ducting at £85 a roll. Do I really need the expensive stuff? Link to comment Share on other sites More sharing options...
Oz07 Posted February 6, 2020 Share Posted February 6, 2020 I did. Again, probably got hoodwinked but thought that's the part you can't change when in Link to comment Share on other sites More sharing options...
Triassic Posted February 8, 2020 Author Share Posted February 8, 2020 (edited) Can anyone explain anti-static plastic ducting, what makes it anti-static? Edited February 8, 2020 by Triassic Link to comment Share on other sites More sharing options...
SteamyTea Posted February 8, 2020 Share Posted February 8, 2020 12 minutes ago, Triassic said: Can anyone plain anti-static plastic ducting, what makes it anti-static It is to do with the outermost shell of electrons on the polymer molecule. (I really have no idea what I just said there) Link to comment Share on other sites More sharing options...
Triassic Posted February 8, 2020 Author Share Posted February 8, 2020 So the plastic duct is coated inside with something? Link to comment Share on other sites More sharing options...
SteamyTea Posted February 8, 2020 Share Posted February 8, 2020 Probably. Silver is a common antibacterial coating. It has a lot of electrons, but the outermost shell only has one. This is why it reacts with other atoms so well. Link to comment Share on other sites More sharing options...
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