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Cpd

MvHr in cottage refurbishment

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Ok so please lets just take this one step at a time, i am here to listen and learn and hopefully make the right decisions when the time comes. (Unless i have already made the wrong ones....) I have two houses both are 1.5 storey and both right next to each other. The house i live in is very basic, very traditional and in need of a lot of maintenance and improvements over a long period of time. However having very small children and a partner pretty much prevents any type of serious work being undertaken. 

 

Winters are the hardest as it has very little insulation and obviously costs a small fortune keep it warm. I am not complaining, i could not be more happy with where i am its just a fact.

 

The cottage has a much better roof and will be suitably airtight by the time i finish redoing the insulation. 

 

I would like to get the cottage to a point where as a family we can live in it during the winter and i can work on the main house without impact on the rest of the family. In the past the cottage has been used by our friends and helpers / volunteers but when its up and running i would like to rent it out as a holiday let during the summer to create some extra funds to help pay for the main house improvements. 

 

I aim to install a mvhr unit for whole house ventilation 

 

I have read previous post time and again and i hope i have a much better understanding about mvhr than when it first became an idea for me a few years back. 

 

The cottage is small and the system i hope to design is hopefully going to reflect that. I have a long stay volunteer who is very smart and though not that familiar with mvhr is willing to help me with design as he is smart and can use sketch up. I am very practical and adaptable but i would not call myself smart and i cannot use sketch up. 

 

Hopefully with the collectives help, Mr smarts and my practicality we can design a system that i can install and will work as hoped. 

 

Being a small house the only place for the unit is in the stairwell. There is plenty of height so it does not impose on users and with some quirky wood work i can make it look right at home. 

 

I will gather all the information i need together in a presentable form and will then start asking questions. I already have an mvhr unit as it was super cheep on ebay.  Its oversized but can be adjusted according to requirements.  

 

Just a few of Mr Smarts screen shots from Sketchup. As i said i will get all the info together and come back to ask questions. Please be patient with me on this one. 

 

 

 

 

 

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It may well be worth you getting an air leakage test done, that way you know where you are starting from.

You could make your own fan and manometer/pressure gauge if you are fairly practical and save yourself a few quid.

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1 hour ago, SteamyTea said:

It may well be worth you getting an air leakage test done, that way you know where you are starting from.

You could make your own fan and manometer/pressure gauge if you are fairly practical and save yourself a few quid.

Combined with a smoke machine will soon identify where the bad air leaks are so they can be plugged. 

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Ok i have the means and ability to make a fan and smoke would give a clear indication of air leakage, i first need to finish rebuilding the front and back doors block up the unused chimney and complete the insulation upgrade. I am trying to make sure that i have all my duct runs confirmed before i inadvertently block off potential pathways, i need to get the upstairs bedrooms back to habitable so that the volunteers can come back in from outside....... its not that bad but i would like to have sleeping space for them again this summer. The rest of the refurb will be going around them. Thats why i need to make some assumptions on air tightness at this time and make sure i have the hardware installed but not commisioned. 

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The big mistake just about everyone makes with old Scottish croft houses, is to make a "plasterboard tent" inside them.

 

I can almost guarantee that when I remove a switch or socket from the wall a howling gale will emerge from the hole.  In almost every case, the framing and plasterboarding that lines the walls is open up into the loft space from where cold air can get between the wall and the plasterboard. 

 

Add to that, most have no insulation at all in the room in roof ceilings, no wonder they are cold.

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@ProDave i am very aware of what you are saying and the cottage though a very traditional croft house is not going to be a plasterboard tent. I am in total controle and have a full understanding of the importance to detailing in many aspects of the refurbishment and try to educate myself before making mistakes. Eventually this will be a fantasric little summer holiday cottage but have the ability to house me and my family over the winters  when i will have a chance to start addressing the wooden panelled tent we live in at the moment. 

The aim of this thread is to share my ideas, bat them about and come to a conclusion. With all you great people out there i am sure i can come up with something that may not be perfect in everyones eyes but will be the best of what i can do with the materials i have or can afford to get. 

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@Crofter    I got this one for £300 new of eBay it can do up to 370m3 and my place is shy of 250m3 so i assumed.... this would be a bit big but it has the ability to be wound right back so hopefully... providing minimal work and good efficiency but have the ability to boost from kitchen and bathroom on a humidistat or switch..... it was my first “risky” buy of ebay and i am yet to understand the consequence of that decision......  

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@Cpd I wasn't trying to imply you were going to do a poor job, just mentioning that the vast majority of builders do.  One in particular I rewired a few years back,  builder doing the refurb "insulated" it by including 25mm thick kingspan behind the pasterboard (still the usual plasterboard tent behind that kingspan)  He genuinely thought he was doing a good job. He even told me that when he did his own house, he went overboard and fitted 50mm thick kingspan to insulate his plasterboard tent.

 

It will be interesting to see how you make a proper job of doing it.

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@JSHarris thanks for the spread sheet. It will be very useful  to help me understand and clarify information for both my thread on the AsHp and this thread on MvHr My first question is about efficiency of the Mvhr unit do i enter the efficentcy as stated on the machine or does one down grade the manufactures figures to “real life” expectations ? 

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Best to use the efficiency that's given in the SAP database for the MVHR unit, that should be pretty close to reality.

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