Heat Recovery Air Ventilation System (HRAV)

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carrotcake

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Hello,
I wonder has anyone installed this system in their house? If so, how are you finding the system and does it take a lot of work to maintain (i.e. regular cleaning of filters). I am putting in geothermal underfloor heating and I have been advised to install this HRAV system by my architect but the geothermal people are saying I should not to so as there is a lot of work involved in the maintenance of it and that I should just open the window instead if I need some air!! Help!
Thanks a lot.
 
Building regs require ventilation, opening windows isn't good enough.

There are a few pervious threads on this topic, the search facility should help you find them.
Leo
 
A HRV system will work very well with your geothermal heating system. In fact it will reduce your heat loading as stale warm extracted air will heat incoming fresh air. In order for a HRV to work correctly the room volume is calculated so as to give 2 air changes per hour or approx 30 Litres/second at the extract locations.
The British Standard Part F I think on ventilation gives you detailed calculations.
The traditional methods of ventilation, Opening windows and using wall vents is not energy efficient as the heat loss in these locations will be high.
I will be installing a HRV system in my own self build next year. Even though the initial investment is high you have a auxillary heating system and a fresh air supply system all in one unit. Its a no brainer!!!!!!!!!!!!!!
 
Rahman, are there any specific features you should look out for/avoid when looking at HRAV systems? Have you decided on a specific make yet or still looking? Thanks.
 
Leo said:
Building regs require ventilation, opening windows isn't good enough.

There are a few pervious threads on this topic, the search facility should help you find them.
Leo
Click to expand...

These HRV systems are specifically designed to give you the necessary ventilation, whilst being eternally more eficient than 'passive' wall vents. These 'hole-in-the-wall' vents are an out dated method of ventilation and should not be used.
 
BarneyMc
You should ensure that the HRV system has the following features
  • All ducting should be well insulated to ensure no build up of condensation within the ducts. Also check that the duct material is non-shedding
  • The HRV unit itself should allow the panel filter on the supply side to be changed out easily for cleaning.
  • The motor on the supply and extract fan should be Ex rated and also have a thermistor fitted to prevent overheating so that the risk of fire is minimised. In most cases the HRV unit will be in the attic space.
  • Check that there is a guarnatee and perhaps the first maintenance should be free.
  • All wet areas kitchens, bathrooms should be the extract locations with a boost facilty in bathrooms to remove steam from showers, baths etc quickly.
  • The size of the unit should allow 3 air changes per hour in each room.
Theres a company in Tuam called Proair (no connection) and I am going with them for my system
 
We have geothermal heating and the HRAV as we were advised to do so by our geothermal contractor and architect. We have been in 10 months and have had no hassle, or problems. We had a small problem with a switch for the ventilation about a month ago and the company (proair in Tuam as mentioned), came out within a couple of days, sorted it out and changed the filters at the same time.
Another major benefit that we noticed is that smells don't linger in the house as normally happens. After painting the inside of the house, the smell was barely noticable within a short space of time.
I would definitely recommend it.
 
pops said:
Another major benefit that we noticed is that smells don't linger in the house as normally happens. After painting the inside of the house, the smell was barely noticable within a short space of time.
I would definitely recommend it.
Click to expand...

What about external smells? We live in a rural area and would often have farmers spreading in the vicinity. Would these be brought in to the house with a HRV unit?
 
Not that I have ever noticed. Smells would be more likely be brought in by open windows or doors in my opinion.
 
DoctorEvil said:
What about external smells? We live in a rural area and would often have farmers spreading in the vicinity. Would these be brought in to the house with a HRV unit?
Click to expand...

if your 'passive' vents dont allow in the smells, then the HRV system wont...
 
sydthebeat said:
These 'hole-in-the-wall' vents are an out dated method of ventilation and should not be used.
Click to expand...

We currently have a big problem with musty smells in bedrooms, wet on the walls, damp bed clothes, milldew etc. I have been told his is a condensation problem as there are no vents in any of the rooms.

I was going to get knock out some of the walls and put in a traditional vent. Is this the wrong thing to do??

sorry for slight hijack of your post
 
Its the cheapest method....

your options are:

1. 'hole in the wall' vents
2. replacing your windows with ones with 'trickle' vents incorporated.
3. Introducting 'passive stack' vent systems from rooms. (these vent from grills in your room ceilings to roof vents... ie no knocking large chunks out of your walls..... may suit a rubble or stone wall build.

The HRV system may be uneconomical for your situation as it really is suited for high spec insulated buildings.
 
Thanks sydthebeat!

Of the three mentioned which would you recommend?

The house we are currenlty in is very bad with mildew and wet clothes etc.
We are buying a house in the same estate and I am worried we'll have the same problems.

Changing the windows would be costly I presume so would prefer to avoid this if possible.

I'd like to get this sorted before we move in.
What do you advise?
Thanks
 
assuming windows are too expensive, then HRV would also be,.... (probable installation costs of 6K....)

is the dwelling 2 storey?? if so 'hole in the wall' type is really your only avenue.

if you are buying it, did you get a proper survey done?? did the surveyor make any recommendations.... i hope the vendor is taking these refurbishment works into account in the sale price.....
 
Do these systems eliminate the planning enforcement of either using window trickle or wall vents?

Can they be activated/deactivated on a room per room basis as required, e.g. turn off for rooms that are not being used that day?
 
Barney,
These systems are an alternative to trickle or wall vents.. not an elimination.

They do not take into account whether a room is being used or not.. the same way passive vents dont. The system works by taking stale warm air from 'wet room' areas... this warm air is used to heat the fresh air entering the rooms.. therefore you dont need to heat the fresh air.... (well, 70 - 80% of it).... whereas you do with passive vents.
 
sydthebeat said:
Barney,
These systems are an alternative to trickle or wall vents.. not an elimination.
Click to expand...

... please explain... if HRV systems are alternatives then they can eliminate the need for trickle vents etc right....... or is it that you still need trickle vents anyway?
 
they are an alternative, you can use a HRV system instead of passive vents.

elimination insinuates to me that youre not incorporating ventilation.
 
Well we got our survey done and the guy said there was nothing wrong structurally wrong with with house but that it was very poorly insulated. He said that this would cause condensation and all the issues we are currently experiencing. Hole in the wall vents will just make the room very cold and will not do the job 100%

To fix it you would have to insulate the house properly, dry line the whole place and this would loose 4 inchs off all rooms.
He said he wouldn't buy it.
Is this going to be the case with all old houses? This one was built in 1970

However its the only estate in the area we want that we can afford.
Would we be mad to take on the job of properly insulating the house?
Any ideas on cost?

Thanks
 
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