Our_Valleys_build Posted January 28, 2019 Share Posted January 28, 2019 I may consider a heat recovery system if it has proven worth? What’s people’s thoughts on it and anybody know of any good quoters for the gear? Thanks Link to comment Share on other sites More sharing options...
ProDave Posted January 28, 2019 Share Posted January 28, 2019 I would say 100% yes worth doing. Our last house was quite well insulated, but with standard extract fans, it had something like 8 "holes" in the building for all the required ventilation. The result was on a windy day it was noticably colder as the place was massively over ventilated. Our new house has mvhr and is way more energy eficcient. Partly as a result of better insulation, but also as a result of much lower ventilation heat losses due to the mvhr. Link to comment Share on other sites More sharing options...
Our_Valleys_build Posted January 28, 2019 Author Share Posted January 28, 2019 That’s good to know, are they expensive? I like the idea of circuitlating warm air around the house. I was looking for a reliable company to source materials Link to comment Share on other sites More sharing options...
Declan52 Posted January 28, 2019 Share Posted January 28, 2019 Try https://www.bpcventilation.com Lots on here have bought from them. It's not a difficult thing to install yourself so can be a money saver. Don't look at it as a heat saver device, look at it as more a unit that will provide nice clean fresh air and will remove the bad smells. The fact it can also recover some heat is just a bonus. 1 1 Link to comment Share on other sites More sharing options...
Our_Valleys_build Posted January 28, 2019 Author Share Posted January 28, 2019 Il have a look at that and see what they can come up with thanks Link to comment Share on other sites More sharing options...
Gone West Posted January 29, 2019 Share Posted January 29, 2019 11 hours ago, Our_Valleys_build said: I like the idea of circuitlating warm air around the house. The temperature of the air from MVHR supplied to the living areas of the house is lower than the room temperature so it won't feel like warm air coming out of the vent, but it will be warmer than air directly from outside. The only way for the supply air to have a higher temperature is to use a MVHR post heater of some sort. 1 Link to comment Share on other sites More sharing options...
Jeremy Harris Posted January 29, 2019 Share Posted January 29, 2019 As an idea as to the benefit of MVHR, here are a couple of plots of the heat loss rate from our house, the first with MVHR, the second without: The plots show the heat loss from the house versus the difference in temperature between indoors and outdoors. With MVHR the total heat loss rate for 20 deg C indoors and 0 deg C outdoors is about 1,200 Watts. Without MVHR, and assuming the same level of ventilation with trickle vents and extractor fans, the total heat loss rate for the same conditions is just over 2,000 Watts. The MVHR reduces the heating requirement under these conditions by around 40%, a very worthwhile saving off the heating bill. 2 Link to comment Share on other sites More sharing options...
mvincentd Posted January 29, 2019 Share Posted January 29, 2019 I went out to a number of mvhr suppliers and they mostly wanted to sell a ducting system that would have created an installation nightmare...impossibility actually....given the specifics of my house construction. ADM Systems however quickly identified the snags and solutions putting me on the right track. I then paid a £300 design fee which is refundable against a final order. I don't consider that ADM have been any more expensive overall for this approach. I do think that the other quotes I received were worthless due to the unworkability of their proposals. My system is not yet running so I cant reach any final conclusions. 2 Link to comment Share on other sites More sharing options...
scottishjohn Posted January 29, 2019 Share Posted January 29, 2019 (edited) blauberg do a de centralised system which will be easy to fit https://www.ecoenvelope.co.uk/ look under mvhr and see the blauberg system there Edited January 29, 2019 by scottishjohn 1 Link to comment Share on other sites More sharing options...
PeterW Posted January 29, 2019 Share Posted January 29, 2019 24 minutes ago, scottishjohn said: blauberg do a de centralised system which will be easy to fit https://www.ecoenvelope.co.uk/ look under mvhr and see the blauberg system there Thats a pretty poor set of reasons why to use it , and some very dubious reasons as to why to go de-centralised. It also means you get no cross ventilation between rooms that do not have these units, and your air tightness goes through the floor as you punch 10 holes in the envelope. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted January 29, 2019 Share Posted January 29, 2019 These single room units also dramatically lose efficiency when operated at building regs ventilation rates, so much so that they become little better than extractor fans and trickle vents. Link to comment Share on other sites More sharing options...
scottishjohn Posted January 29, 2019 Share Posted January 29, 2019 50 minutes ago, PeterW said: Thats a pretty poor set of reasons why to use it , and some very dubious reasons as to why to go de-centralised. It also means you get no cross ventilation between rooms that do not have these units, and your air tightness goes through the floor as you punch 10 holes in the envelope. your air tightnes goes even with fewer holes --but that is a red herring as you block up mvhr when doing air test and as they will work together balancing in and out with the controller option i feel you are being over critical the man wanted a solution that was easy to fit --thats it Link to comment Share on other sites More sharing options...
Jeremy Harris Posted January 29, 2019 Share Posted January 29, 2019 The problem is that an MVHR has just two holes through the walls, and these are sealed in as much as the nature of distributed MVHR means that the chance of a net pressure differential between the fresh air intake and the stale air exhaust is small. Once you have holes all around the building you will definitely get differential pressure effects that tend to drive air in and out either assisting or impeding the flow at the various cycle times of the independent units. You also still have to meet building regs extract rates from the kitchen, bathrooms, WCs etc, which dramatically reduces the single unit efficiency. I was committed to using in-wall mounted room MVHR units, having been sold on the idea a long time ago. I couln't get the units to comply with building regs without having a massive imbalance in flow, plus the cost was astronomical, as even for our house I would have needed around 8 units. I did calculate the heat loss from these, and it ended up as high as having extractors and trickle vents. They may a good solution for retrofitting as a replacement for existing extractors, as at least they provide a degree of heat recovery, but for a new build I have to say I'm no longer convinced that they are a sensible solution, especially given the relatively high initial cost and the ongoing cost of replacing multiple filters through life, not to mention the very much higher electrical power consumption from having lots of small fans running, rather than just two, larger (and hence much more efficient) fans. Link to comment Share on other sites More sharing options...
scottishjohn Posted January 29, 2019 Share Posted January 29, 2019 I certainly won,t be fitting them to my new build ,but will design it so i can run ducting. Its the old story design eveything before making anything and there willalways be compromises along the way . the way the yanks use to build houses was quite good .they would have a "wet wall" . which meant on one side of house -- north in this country you have a walk way behind actual living area for all services to go in from floor to floor which made maintaince + remodelling very easy Link to comment Share on other sites More sharing options...
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