SBMS Posted June 9, 2022 Share Posted June 9, 2022 8 hours ago, joth said: Ours was installed a bit over a year ago and here's the stats from its built in data logging. 249 kWh consumed running the ASHP 6724 kWh energy saved through heat recovery. So about £700 saved over one year and a bit (assuming our ASHP COP 3 would have provided the heat otherwise) That’s really useful @joth it’s great to see some real world data. Makes me wish we had gone for a zehnder as I don’t think vent axia’s app shows as much info as this. Link to comment Share on other sites More sharing options...
joth Posted June 9, 2022 Share Posted June 9, 2022 5 hours ago, JohnMo said: You must have a quite large house I assume. You also need to factor in the cost of filters and service costs to get the total savings and a percentage of the hardware and install costs, based on expected life span, say 20 years. Agree filters should be factored in, but probably not the capital outlay as most people prefer to reason about it in terms "years to payback", so the £5000 ours was (design + supply + install) would be 7 years payback for example. (ignoring both future energy price increases and the capital outlay opportunity cost) All this said, their dashboard numbers do seem a bit high. It's only a 151m2 house. In PHPP annual heating demand goes up by about 2200 kWh/yr if I zero out the heat recovery efficiency, so the Zehnder stats seem at least double the expectation. I've really not dug into why at all. Link to comment Share on other sites More sharing options...
Faz Posted June 9, 2022 Share Posted June 9, 2022 On 06/06/2022 at 14:09, Temp said: We installed MVHR even though our house isn't as air tight as recommended. I've no idea if it saves us money and it does use slightly more electricity than we expected. Would I fit one again? 100% yes. None of our previous houses had such a system and all had condensation issues of some sort. Our first few nights in the new house felt like we were camping out under canvas the air was so fresh when waking up. Towels dry quickly in the bathroom so haven't needed the heated towel rail. We dry all clothes on a rack in guest bathroom, don't use tumble dryer or outside line. We also don't have to dust surfaced do frequently. Your experience may vary but we think it's one of the best decisions we made. Just make sure the filters are easy to access and ideally washable as we find they need cleaning every few months. You should see all the muck and bugs they keep from coming in. This 100%. Wasted £500 on a condensing tumble drier - never used it and probably never will as the humidity control with MVHR is awesome. Air is fresh, no condensation, dry stuff indoors in a few hours all year round - it is great. I think these things work best in a new build / total ripout as you can make sure that the bends in the pipes are minimal and in the right places - noise is a common complaint and these are probably mainly in retro fits I imagine. 1 Link to comment Share on other sites More sharing options...
TerryE Posted June 10, 2022 Share Posted June 10, 2022 My experience is of a similar ballpark to @joth's analysis. Yes, the MVHR uses less than 1 kWh / day which is 1 kWh more than trickle vents. But we have a 3 storey detached house built to roughly passive-class standards. We are all electric and haven't installed an ASHP yet because I can't make a payback case. Instead we use a Willis to heat our UFH mainly on E7 cheap tariff over the winter months. Last year we used just over 11,000 kWh electricity in total (over 70% cheap tariff), so yes the MVHR accounts for maybe 3% of our total energy use, but the heat recovery is around 95% and without this our heating requirement would be around 50% higher, so this one is a no brainer for us. Not to mention fantastic air quality throughout the house and free drying room. @JohnMo We do the annual service ourselves and bulk buy the filters, so the maintenance cost is small beer. 1 Link to comment Share on other sites More sharing options...
joe90 Posted June 11, 2022 Share Posted June 11, 2022 On 09/06/2022 at 18:02, joth said: Agree filters should be factored in, I don’t know if it’s because we are very rural but ours have been in and running fir two years and appear as clean as the day I installed them. Link to comment Share on other sites More sharing options...
ProDave Posted June 11, 2022 Share Posted June 11, 2022 38 minutes ago, joe90 said: I don’t know if it’s because we are very rural but ours have been in and running fir two years and appear as clean as the day I installed them. Interesting observation as you have the same unit as me. Ours has been in use about 4 years now. I dutifully turn the unit off and withdraw the heat exchange modules from time to time and the filters are always in good shape. I take them off, give them a bit of a shake outside, give them a hoover to suck any dust out of them, then put them back. I guess one day they will need replacing, but not yet. We too are rural, there is not much population upwind of us, pretty much all the way down the Great Glen to Fort William. 1 Link to comment Share on other sites More sharing options...
JohnMo Posted June 11, 2022 Share Posted June 11, 2022 Ours is on the second set in 9 months, the latest set have been installed for a couple of months. In the sticks, but a couple hundred meters to the main road and very exposed and sandy site. Filters could be our main expense from the looks of it. Link to comment Share on other sites More sharing options...
MJNewton Posted June 11, 2022 Share Posted June 11, 2022 55 minutes ago, JohnMo said: Filters could be our main expense from the looks of it. What are your filters like? Our Titon uses cages which whilst not necessarily intended to facilitate reuse can be opened and closed back up again. This enables me to buy a roll of material so replacement ends up costing just 10s of pence. Link to comment Share on other sites More sharing options...
Roger440 Posted June 11, 2022 Share Posted June 11, 2022 On 08/06/2022 at 20:34, MJNewton said: We've got 75mm semi-rigid ducting and it is absolutely silent in use, even on boost. I wouldn't consider using anything else. Im struggling with the absolutely silient bit. So, middle of the night, on a still night, you cant tell the difference with it on or off? Link to comment Share on other sites More sharing options...
JohnMo Posted June 11, 2022 Share Posted June 11, 2022 7 minutes ago, MJNewton said: What are your filters like? Our Titon uses cages which whilst not necessarily intended to facilitate reuse can be opened and closed back up again. This enables me to buy a roll of material so replacement ends up costing just 10s of pence. We have two Titon units, one has the filters you are referring to, the other is a pleated filter in a card frame. Will have to get some filter roll and see what I can do for the card framed filters. Link to comment Share on other sites More sharing options...
MJNewton Posted June 11, 2022 Share Posted June 11, 2022 (edited) 28 minutes ago, Roger440 said: So, middle of the night, on a still night, you cant tell the differewnce with it on or off? Not from the ducting itself. The only noise is from the outlets - presumably a combination of the airflow and fan noise, although there is a silencer to help attenuate the latter. Even the noise that is present is hard to hear and only noticeable up close, more prominent on boost of course. Edited June 11, 2022 by MJNewton Link to comment Share on other sites More sharing options...
SteamyTea Posted June 11, 2022 Share Posted June 11, 2022 (edited) Read this just before I left work, got me thinking. My car gobbles about 100,000 m2 of air every 20,000 miles. That is about 600 hours driving for me. Now I have just bought a new air filter for it and it cost £8 from eBay (my fuel consumption has dropped about 5% recently, so time for a change and it has dons about 30,000 miles). Converting that into litres per second that is ~45 litres.s-1 for 600 hours, about 25 days worth, cost at that flow rate would be £113/year. Anyone got any total flow rates for their MVHR? Edited June 11, 2022 by SteamyTea Link to comment Share on other sites More sharing options...
jack Posted June 11, 2022 Share Posted June 11, 2022 37 minutes ago, Roger440 said: Im struggling with the absolutely silient bit. So, middle of the night, on a still night, you cant tell the difference with it on or off? We can hear ours a bit on boost, but not even a whisper when it's on its basic setting. No way I'd be able to tell if it was on or off. Link to comment Share on other sites More sharing options...
SteamyTea Posted June 11, 2022 Share Posted June 11, 2022 (edited) 48 minutes ago, Roger440 said: Im struggling with the absolutely silient bit. I have tinnitus, a bit of noise is helpful. Probably not as good as the World Service, but a lower pitch does mask it. Edited June 11, 2022 by SteamyTea Link to comment Share on other sites More sharing options...
JohnMo Posted June 11, 2022 Share Posted June 11, 2022 28 minutes ago, SteamyTea said: Read this just before I left work, got me thinking. My car gobbles about 100,000 m2 of air Anyone got any total flow rates for their MVHR? Should that be 100,000 m3? My main MVHR unit flow 190m3/h. The filters should really last 12 months. They are £40 a set delivered. 190 X 24 X 365 = 1,664,600 m3/a for £40, although mine last 6 months so £80/year. Link to comment Share on other sites More sharing options...
SteamyTea Posted June 12, 2022 Share Posted June 12, 2022 7 hours ago, JohnMo said: Should that be 100,000 m3? Think so. Was only rough mental calculations. Filter is quite small on the Ford. Link to comment Share on other sites More sharing options...
RobLe Posted June 12, 2022 Share Posted June 12, 2022 Our VA sentinel kinetic plus bh averages at 100m3/hour. When we’re in it’s more, when we’re out it’s less, it goes up and down based on humidity and CO2. The filters get changed every 3 or 4 months - that’s when it starts nagging. I pull out the old filters, take the fabric off the metal frame, clip on a new bit of fabric with ‘supaclip’ clips. Piccy of an old one about to be changed: Link to comment Share on other sites More sharing options...
joe90 Posted June 12, 2022 Share Posted June 12, 2022 58 minutes ago, RobLe said: Piccy of an old one about to be changed: Wow, is that dirt? Just goes to show what you would be breathing/cleaning. Link to comment Share on other sites More sharing options...
SteamyTea Posted June 12, 2022 Share Posted June 12, 2022 33 minutes ago, joe90 said: Wow, is that dirt? Just goes to show what you would be breathing/cleaning. Till you light the fire. Link to comment Share on other sites More sharing options...
joe90 Posted June 12, 2022 Share Posted June 12, 2022 31 minutes ago, SteamyTea said: Till you light the fire. Well it’s interesting that my filters are still clean after two years even with the fire lit during winter 🤷♂️ Link to comment Share on other sites More sharing options...
SteamyTea Posted June 12, 2022 Share Posted June 12, 2022 2 minutes ago, joe90 said: Well it’s interesting that my filters are still clean after two years even with the fire lit during winter 🤷♂️ Do you have filters on the outlets then? More seriously, if they are clean, there may not be enough flow though them. Does the local farmer plough, rake and harvest crops? Link to comment Share on other sites More sharing options...
joe90 Posted June 12, 2022 Share Posted June 12, 2022 2 hours ago, SteamyTea said: Does the local farmer plough, rake and harvest crops? Only grass cutting for silage mostly. Link to comment Share on other sites More sharing options...
Gone West Posted June 12, 2022 Share Posted June 12, 2022 5 hours ago, SteamyTea said: More seriously, if they are clean, there may not be enough flow though them. Does the local farmer plough, rake and harvest crops? That's interesting because when we lived in Kent the farming was arable and fruit and our MVHR filters and our windows became quickly dusty. Around here it's grass with cattle and sheep and sometimes silage and there's virtually no dust on the windows. Maybe one day, if appropriate, we'll have a MVHR again. Link to comment Share on other sites More sharing options...
SteamyTea Posted June 12, 2022 Share Posted June 12, 2022 7 minutes ago, Gone West said: Around here it's grass with cattle and sheep and sometimes silage and there's virtually no dust on the windows. I get a lot of salt, and dust from the Sahara. I am a few miles from the South Coast, couple of miles from the North Coast, and 200 meters high. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted June 12, 2022 Share Posted June 12, 2022 4 hours ago, SteamyTea said: I get a lot of salt, and dust from the Sahara. Wonder why it wants to drop on your bit of Cornwall - just south of Zennor. Link to comment Share on other sites More sharing options...
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