Pocster Posted June 28, 2019 Author Share Posted June 28, 2019 25 minutes ago, Simplysimon said: glad i read this, i have seen enthalpy mentioned but not researched it. i think for the additional cost (£200) i'll have it fitted. I’m still not sure even what this is and the benefits.... Link to comment Share on other sites More sharing options...
Simplysimon Posted June 28, 2019 Share Posted June 28, 2019 2 minutes ago, pocster said: I’m still not sure even what this is and the benefits.... takes the moisture out of the stale air and puts it back into the house rather than down the drain. https://www.zehnder.co.uk/products-and-systems/comfortable-indoor-ventilation/enthalpy Link to comment Share on other sites More sharing options...
Pocster Posted June 28, 2019 Author Share Posted June 28, 2019 3 minutes ago, Simplysimon said: takes the moisture out of the stale air and puts it back into the house rather than down the drain. https://www.zehnder.co.uk/products-and-systems/comfortable-indoor-ventilation/enthalpy Now I’m confused ! I thought mvhr took the stale air and moisture out - used the heat for incoming . Why cycle the moisture back into the house ? Link to comment Share on other sites More sharing options...
Simplysimon Posted June 28, 2019 Share Posted June 28, 2019 2 minutes ago, pocster said: Now I’m confused ! I thought mvhr took the stale air and moisture out - used the heat for incoming . Why cycle the moisture back into the house ? keeps the air from drying out. your house will have a humidity, which will vary between rooms, a dry room will be unpleasant. Link to comment Share on other sites More sharing options...
Pocster Posted June 28, 2019 Author Share Posted June 28, 2019 Just now, Simplysimon said: keeps the air from drying out. your house will have a humidity, which will vary between rooms, a dry room will be unpleasant. Ok , why don’t the mvhr companies push this ??? . Just wondering as they don’t seem to mention it .... Link to comment Share on other sites More sharing options...
Onoff Posted June 28, 2019 Share Posted June 28, 2019 9 minutes ago, pocster said: Now I’m confused ! I thought mvhr took the stale air and moisture out - used the heat for incoming . Why cycle the moisture back into the house ? You don't want things getting too dry. Link to comment Share on other sites More sharing options...
Simplysimon Posted June 28, 2019 Share Posted June 28, 2019 1 minute ago, pocster said: Ok , why don’t the mvhr companies push this ??? . Just wondering as they don’t seem to mention it .... totally agree Link to comment Share on other sites More sharing options...
Pocster Posted June 28, 2019 Author Share Posted June 28, 2019 1 minute ago, Simplysimon said: totally agree ? i’ll Send them an email and find out ! Link to comment Share on other sites More sharing options...
PeterW Posted June 28, 2019 Share Posted June 28, 2019 7 minutes ago, pocster said: Ok , why don’t the mvhr companies push this ??? . Just wondering as they don’t seem to mention it .... Because they are difficult to explain and expensive to produce ..! They are also a little more fragile than standard heat exchangers. 1 Link to comment Share on other sites More sharing options...
Pocster Posted June 28, 2019 Author Share Posted June 28, 2019 14 minutes ago, Onoff said: You don't want things getting too dry. Surely the incoming ( outside air ) is ok as in not dry ? Link to comment Share on other sites More sharing options...
ragg987 Posted June 28, 2019 Share Posted June 28, 2019 When cold outside, the relative humidity (UK) is quite high, but when heated in the heat exchanger it drops. In the meantime the stale, warm and wet air on the house is cooled and so gets to saturation, hence condensation and water drains out. The enthalpy part will remove the moisture from extract and add to supply. Is it really needed? We don't have this, the relative humidity inside is between 40 to 50% and quite comfortable. Perhaps people with some skin conditions might benefit from higher humidity? Not sure. 1 Link to comment Share on other sites More sharing options...
Oz07 Posted June 28, 2019 Share Posted June 28, 2019 43 minutes ago, Onoff said: You don't want things getting too dry. Totally agree Link to comment Share on other sites More sharing options...
lizzie Posted June 28, 2019 Share Posted June 28, 2019 The RH inside my house would often drop into the mid twenties, it caused cracked lips and nosebleeds amongst other things. It made very uncomfortable living at that level of dryness. My optimum RH for my health is a few percent either side of 50. We rarely got above mid 40’s even in wet weather and mid 30’s was the norm. We are a 200sqm single storey with just two occupants (one of whom out all day) plus woofer. One bath, one shower, not a lot lot of ‘wet’ cooking (although at one stage I was boiling pans of water to try and get humidity up and I bought a humidifier too which was a chinese rubbish job). The level of activity in the house did not create much moisture and that may have contributed to our very dry atmosphere plus our exposed windy location. Retrofitting the enthalpy unit - even though expensive- has changed the house totally. We now sit at about 50% RH on average and the house is much more comfortable. Best retro money I have spent only wish I had specced it at the start but I was told I wouldn't need it when I asked. 1 Link to comment Share on other sites More sharing options...
ProDave Posted June 28, 2019 Share Posted June 28, 2019 11 minutes ago, lizzie said: The RH inside my house would often drop into the mid twenties, it caused cracked lips and nosebleeds amongst other things. It made very uncomfortable living at that level of dryness. My optimum RH for my health is a few percent either side of 50. We rarely got above mid 40’s even in wet weather and mid 30’s was the norm. We are a 200sqm single storey with just two occupants (one of whom out all day) plus woofer. One bath, one shower, not a lot lot of ‘wet’ cooking (although at one stage I was boiling pans of water to try and get humidity up and I bought a humidifier too which was a chinese rubbish job). The level of activity in the house did not create much moisture and that may have contributed to our very dry atmosphere plus our exposed windy location. Retrofitting the enthalpy unit - even though expensive- has changed the house totally. We now sit at about 50% RH on average and the house is much more comfortable. Best retro money I have spent only wish I had specced it at the start but I was told I wouldn't need it when I asked. I wonder what it was about the house that made it so dry? We are 150 square metres, 3 humans and one feline. Plain ordinary house no special measures and RH sits between 50 and 60% most if the time. Link to comment Share on other sites More sharing options...
lizzie Posted June 28, 2019 Share Posted June 28, 2019 3 minutes ago, ProDave said: I wonder what it was about the house that made it so dry? We are 150 square metres, 3 humans and one feline. Plain ordinary house no special measures and RH sits between 50 and 60% most if the time. No idea its just usual MBC house but we are high on a ridgeway so quite exposed that may be partly responsible. Link to comment Share on other sites More sharing options...
dpmiller Posted June 28, 2019 Share Posted June 28, 2019 wasn't there something wrong with the way the house was set up tho? Link to comment Share on other sites More sharing options...
epsilonGreedy Posted June 28, 2019 Share Posted June 28, 2019 2 hours ago, PeterW said: Because they are difficult to explain and expensive to produce ..! They are also a little more fragile than standard heat exchangers. Is there any risk of an enthalpy unit becoming a breeding site for microbes? Link to comment Share on other sites More sharing options...
lizzie Posted June 28, 2019 Share Posted June 28, 2019 43 minutes ago, epsilonGreedy said: Is there any risk of an enthalpy unit becoming a breeding site for microbes? No they have microban linings Link to comment Share on other sites More sharing options...
Gone West Posted June 29, 2019 Share Posted June 29, 2019 10 hours ago, ProDave said: I wonder what it was about the house that made it so dry? Living near the sea or in an enclosed site with water nearby usually means higher humidity. So being inland on an open site presumably means lower humidity. Link to comment Share on other sites More sharing options...
SteamyTea Posted June 29, 2019 Share Posted June 29, 2019 On 28/06/2019 at 12:45, lizzie said: do you know how would I go about linking one as a retrofit....is it even possible? Relatively easy to make one with a cheap sensor (DHT22), a cheap board (RaspberryPi Zero or similar) and a solid state switch. With that kit you can also easily expand and add extra sensors i.e air pressure, light sensing, energy monitoring and do some data logging. Quite fun learning how it all works and there are a few people on here that know it inside out. Link to comment Share on other sites More sharing options...
Conor Posted June 30, 2019 Share Posted June 30, 2019 (edited) My neighbour designs and installs ventilation systems. He's installed various types and currently recommends maico. They have fully automated functioning, VOC, CO2, humidity, temperature sensors that control flow rate. You can programme your own modes through the app, e.g. when humidity hits a certain point, it can trigger a change in flow rate. Also have the semi permeable heat exchanger that help with humidity. I've not looked in to MVHR systems at all yet, so not been able to do a comparison. His reason for liking them is the range of control and high level of automation. Fit and forget. Apart from filters.... https://www.eibmarkt.com/gb/products/Maico-Central-air-supply-and-exhaust-device-WS-320-K.html Edit. Link to manufacture's pages https://www.maico-ventilatoren.com/en/products/p/ws-470-g51104/ws-470-bet-p113724/ The units with "E" in the name are the enthalpic. Ones with "K" have anti frost pre heaters. Edited June 30, 2019 by Conor 1 Link to comment Share on other sites More sharing options...
Jeremy Harris Posted July 1, 2019 Share Posted July 1, 2019 The programmable humidity sensor and switch I used was this unit from Poland: https://www.ebay.co.uk/itm/DHC-100-Feuchtigkeitsregler-Hygrostat-Humidity-Control-Sensor-Fuhler-2-meter/182951476628?hash=item2a98c1fd94:g:hAgAAOSwFSxaKeA~ I put the remote sensor inside the extract plenum chamber and it seems to work well. Boost turns on within a few seconds of a shower starting, or even just from the steam from making a cup of tea, and the unit can be programmed with a variable turn off delay and RH hysteresis. I fitted the controller inside a surface mount box, in the services room, just above the MVHR: 1 Link to comment Share on other sites More sharing options...
lizzie Posted July 1, 2019 Share Posted July 1, 2019 @JSHarris thank you very much...I have just ordered. Link to comment Share on other sites More sharing options...
Pocster Posted July 1, 2019 Author Share Posted July 1, 2019 Well here’s the reply ..... doesn’t seem to address dryness of air hope this information explains things A Mechanical Ventilation Heat Recovery (MVHR) system is an energy recovery ventilation system that uses an air-to-air heat exchanger that recovers heat that is usually wasted. It works by supply and extracting airflows in and out of homes and buildings to ensure a better indoor air quality. Heat recovery units can recover up to 90% of normally lost heat depending on the unit and the application. A MVHR system works independently from a heating system and due to the heat recovery feature, it can have great savings on your energy bills. A MVHR system works to eliminate condensation and mould within a building by constantly ventilating a property. By eliminating condensation, it also eliminates the risk of damage to the structure of a building and stops the build up of mould and damp. MVHR systems are suitable for small residential products to large commercial projects. Link to comment Share on other sites More sharing options...
Gone West Posted July 1, 2019 Share Posted July 1, 2019 9 hours ago, JSHarris said: The programmable humidity sensor and switch I used was this unit from Poland: https://www.ebay.co.uk/itm/DHC-100-Feuchtigkeitsregler-Hygrostat-Humidity-Control-Sensor-Fuhler-2-meter/182951476628?hash=item2a98c1fd94:g:hAgAAOSwFSxaKeA~ I put the remote sensor inside the extract plenum chamber and it seems to work well. Boost turns on within a few seconds of a shower starting, or even just from the steam from making a cup of tea, and the unit can be programmed with a variable turn off delay and RH hysteresis. I fitted the controller inside a surface mount box, in the services room, just above the MVHR: I bought one of those and it's still sitting in it's box unused. I have never found it necessary to increase the extract fan speed. 1 Link to comment Share on other sites More sharing options...
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