Cimbined Solar and house ventilation

cts

Hi, my house is late 1970's vintage, 2500 sq ft bungalow, cavity wall, dg pvc windows/doors, oli fired CH, with 3 zones (dhw, living area and bedrooms(4)). In the winter we regularly get a lot of condensation buildup on windows especially in the bedrooms. The windows are opened daily but need to be closed when heating in on. We also have slight black spotting on the back of the curtain lining. We have a long roof almost due south and plenty of room in the attics space. The cavity is pumped with bead insulation and 250mm fiberglass in attic. The floors are concrete (uninsulated).
I'm thinking of getting a HRV system installed but would also like to incorporate a solar element to it. I believe such systems exist and wouls really appreciate any nuggets you may have to help me understans all the issues, benefits etc etc.
Tia.

sinnerboy

HRV is counterproductive i.e will cause you to lose heat if the building is not very air tight . your house will not be very air tight

Do you have curtains located to prevent heat from rads flowing over windows ? - if so try leaving them open - just to see what differnce is made to condensation . how are the seals of the frames - if degraded they could be part of the problem

cts

I'm curious, why do you say the house is not airtight? What is the maximum airtightness allowed for effective HRV?

The windows are not that old and look good (no visible seal degradation) The curtains are generally pulled at night. I wont be able to test this until next winter and I want to have it sorted by then if possible.

sinnerboy

houses weren't built to good levels of air tightness in the '70's

you need a rate of 3m3 / hr / m2 for HRV ( max 4 ) at delta 50 paschals

needs carefull spec and workmanship to achieve this

if determined to install HRV , first do 2 air tightness tests

1. to find leaks . then fix them
2. then re test . if you don't achieve level above - abandon the idea

sinnerboy

try pulling curtains away from rads i.e draw them but put stools or chairs or similar to stop curtains choking the heat flow across the windows - see if it makes any difference

cts

Hi Sinnerboy, I have had the house tested for airtightness. There were a few leaks found but still the average ACH at 50 pa was measured to be 3.18!

Based on your earlier posts, it would seem that I could benefit from a HRV system and would appreciate any info on such systems involving solar as well. What should I be looking out for? What questions do I need to be asking? Tia

sinnerboy

Excellent ! I am surprised but please for you

There are some excellent links here to SEI . Look at the SEI Phase 2 Solar registered list .

Talk to the suppliers there about linking to HRV

http://www.boards.ie/vbulletin/showthread.php?p=56199608#post56199608

sinnerboy

Tia - can i ask what the test cost you ?

MickLimk

Not 100% clear about what it is you're looking for. It is a combined HRV/Solar water/air heating system like this (http://www.sunwarm.com/sunwarm.shtml) or something else?

If it's something like what's in the link above, it did get mentioned in a few threads a while back but it doesn't seem to have come up since. Have a look here and see what was mentioned about it in the last two years. Might be worth PM'ing the one guy who says he knows someone who installed it...

http://www.boards.ie/vbulletin/archive/index.php/t-2055102875.html
http://www.boards.ie/vbulletin/showthread.php?t=2055028970

The sunwarm system (I've no association here!) is on the SEI product list and there are a couple of installers in the Dublin area listed and one up north.

Don't want to knock the system above as I know nothing of it but it may be simpler to install two independent systems, a dedicated HRV and a solar water heating system? Worth pricing both options at least.

cwboy

Can someone explain how the solar and hrv would be linked? What are the benefits? In the process of building and going to incorporate both these so any would like to get the max benefits thanks

MickLimk

The only linked HRV/Solar water heating system that I've come across is the Sunwarm one mentioned above and personally I don't see the benefit. Their system works on the basis of passing air through the solar panels, forcing this air through an air-to-water heat exchanger in the HRV unit and then feeding the remaining warm air into the house. The warm water generated by the air-to-water heat exchanger is pumped through a coil in a cylinder as it would normally be in a regular solar system.

I'd like to see their certification to see what kind of efficiency numbers are given as well as the output power per year (kWh/m2/yr). The reason I'd be sceptical about the efficiencies of this particular system (or any similar one based on the same technologies) is due to it's heat transfer method. I can't imagine that using air as the heat exchange medium from the panel is as good as a water/antifreeze mix that would be used in a regular solar water heating system.

I think both HRV and solar water heating can be great systems but I'd keep the two separate. My worry about a combined system would be that you would end up with a system that was compromised and would not be as efficient as a dedicated HRV working independently from a dedicated solar hot water system. Cost would also be something worth looking closely at. I don't know what the going rate for a decent HRV system being installed into a new house but I've seen the average price for the Sunwarm system quoted as €16,485 for a 200m2, two-storey house.

By the way, these guys do a system that doesn't have the solar water aspect to it. It still uses solar panels to heat the incoming air in conjunction with the HRV but doesn't have an air-water heat exchanger. This is called the 'Sunwarm Air' and may be what the OP was looking for...

Mods: I don't want to be seen to be picking on a particular brand but it was the only one of this type that I've come across so feel free to edit/delete this as you see fit.

sinnerboy

think in 1st principles

solar panels work best in summer - to provide "free" hot water ( free after the capital cost is paid off by fuel savings )

good HRV units can recover up to 90% of heat

So on that sharp -4 degrees frosty Jan morning - overcast -

Solar panels will be doing - not much .

HRV will be recovering 90 % of heat ( from your cosy well heated and well insulated interior )

And on warmer days like we have been having just now ....

Solar panels will do what they do best - heat your hot water cylinder . Would you want to divert some of that heat energy to the HRV unit - don't think so

cts

sinnerboy wrote: »

Tia - can i ask what the test cost you ?

No Prob. The test (air tightness and Thermal imaging) cost Eur 750. Very comprehensive. The thermal imaging showed up some sinking/loss in the cavity wall insulation (about 2 ft from ceiling).

muckety

Who did you get to do this air tightness & Thermal imaging test? I'd like to get something similar for our house to see where we are losing heat. Is this the point of it?

cts

muckety wrote: »

Who did you get to do this air tightness & Thermal imaging test? I'd like to get something similar for our house to see where we are losing heat. Is this the point of it?

You can PM me for the company detail as it is not allowed to give details on the public board. I am based in West Cork and the survey was carried out by a local energy consultant.
The survey took about 6 hours in total and every aspect of energy use in the house was investigated. I got advise on the heating system, controls, insulation, ventilation, air tightness. The guy had a whole pletora of equipment from moisture meters, small portable smoke machine, contact termocouples, wind speed meter, borescope, blower door machine, and a really cool thermal camera. I have to say that while I initially thought the cost was high, I received more than my money's worth because I now have a great idea of where to and where not to spend my hard earned cash.

sinnerboy

to all reading above - take note !

sinnerboy

Tia , if you would not mind - can you keep us in the loop with your future decisions

cts

Hi sinnerboy,

I've decided to go with dedicated MHRV and seperate solar later.
I have a question on the ducting used for mhrv. I have got conflicting views on the type to use. I would be grateful if I could get some perspectives on the different types (flexible, flat & rigid).

Thanks.