DVS - HRV - MoistureMaster

[tricky]

I've never understood why people spend $1000-$1500 to install these systems.
You can achieve the same result by opening a window at each end of your house and letting the wind blow through.
Nett result - the moist air is removed and your house is colder.
I certainly don't believe the claim that "warm air from your ceiling cavity" is pumped into the house.
At 11pm on a winters night, my ceiling cavity is about 1C. The interior of my fridge is warmer.

[rockran]

How much did you base your decision on the salesperson and the discounted offer, and how much on the system?

No, the HRV system was still more expensive than the DVS system. My decision was purely based on the fact that we close out doors at night and I don't know how DVS would work when the doors are closed. The sales guy didn't give me a good enough explanation.

From what you say the different systems offer quite different services. My understanding is that they are all basically the same.

The systems are essentially the same but they differentiate with each other
a. MM - In line heater
b. DVS - price
c. HRV - Heating from roof

With all the systems you can choose options that will make them exactly the same.

DVS removes moisture from each room. Well so will all the others if you install a vent in each room like you have with DVS.

I went with HRV. HRV says you NEED a vent in every room. DVS & MM say you DON'T. Hence the system is cheaper.

We keep our doors closed at night. Fine, but then you pay extra for extra vents in each room. The type of system does not matter.

Yes see above

DVS has a better filtration system for allegies. Is that what the DVS salesman told you?

HRV does and yes the standard DVS system is not as good as the standard HRV (which cost more). You can add a better filter to the DVS system to make it equivalent to the HRV one and this the DVS guy accepted.

They do not provide heated air. Well they do indirectly by removing moisture, and to an extent they do directly by slightly warming the air as it circulates. Each model will have options for having a heating gadget installed (basically a glorified light bulb). You can choose that or not by paying a little more for a more advanced unit.

HRV says there is heat in your roof. I'm just letting everyone know that in my roof its colder at night and if you think about it.. if a place gets hotter faster it will get colder faster as well.

Yes the air is dryer and fresher.

I'm not trying to knock your decision, rather to question the grounds on which you made it.

Take it or leave it, its my experience having gone thru this. If it helps someone with their decision good on them.

[cube]

I've never understood why people spend $1000-$1500 to install these systems.
You can achieve the same result by opening a window at each end of your house and letting the wind blow through.
Nett result - the moist air is removed and your house is colder.
I certainly don't believe the claim that "warm air from your ceiling cavity" is pumped into the house.
At 11pm on a winters night, my ceiling cavity is about 1C. The interior of my fridge is warmer.

Last week, when the sun was out and the air temperature was around 12-14 degrees, the air in the roof space was between 20 and 28, and the house was noticeably warmer than similar days before we installed Moisture Master.

Opening the windows is fine, except for the

a. howling gale
b. extra noise from the road outside.
c. rain

that accompanies the 'dry' air.

xris - one thing that was interesting about the various sales staff that we spoke to was that they all spoke to their particular system's strengths. When challenged about, e.g. heating or filtering offered by others, they would acknowledge that their system was not equivalent, but that the benefits outweighed the negatives.

All in all, it was interesting how knowledgeable the sales people were about their opposition.

The Moister Master website (www.condensation.co.nz) has a useful FAQ that goes through most of the objections to their system (and therefore the principles involved in all systems of this type).

cube

[whitt]

Warning:

Buy this type of system on the basis of moisture control only.

Any slight heating effect treat as a bonus and you won't be disappointed.

[rueben]

I have been through a lengthly process to decide which system was best for our house. Everyones needs are different.

Condensation was not such a problem with us as we live in a draughty old house - we wanted even heat through the house and good filtration as we live near orchards.

The HRV specifications won hands down. They have a 3 year money back guarantee and stand by their product.

These are the reason we went with HRV.

* The filter is below the fan. Other companies have the filter above the fan - to protect the fan, not the people living in the house. The HRV filter filters to .8 of a micron which didn't mean much to me but apparently 80 microns is a human hair. The other systems have filter similar to a vacuum cleaner - not nearly enough to filter out pollens, sprays, polution and bacteria. This was a huge issue with the allergies we have.

* The HRV Controller is more advanced. You can see at any time what temperature is in the roof. Even on overcast days our roof gets to 21 degrees and our core temperature of our home has risen from 11 on a frosty morning to 17 degrees at the lowest. I would challenge anyone that says there is no heat in your roof during the day in winter. If its cooling your house down at night then call the person who sold it to you as they can be adjusted.

The controller slows down at night so you do not need a heater in the roof cavity,. The reason other products have heaters up there is because their controller doesn't turn the fan down when its cold up there. Whats the point of heating 7 degree air in the roof when the system has blown 24 degree air all day into your home? It is more efficient to top up the air already warmed. HRV never say they replace the heating in your home. They say conservatively 40 - 60% of your heating is supplied for 12 cents per day, per fan.

The reason it costs only 12 cents per day is because it is an 85watt fan that doesn't blow full bore all day - just the times the roof is warmer than your home. I think this is the main selling point of HRV - low cost for getting 40 to 60% of your home heating - fantastic.

* Customer service and knowledge and the product guarantee.

* Number of vents and it being "positive pressure". HRV stops draughts because it is causing a positive pressure in your home. The air is pushed through cracks,etc and dust and smells are pushed out too.

* "burnt toast mode". IF you burn toast or cook fish you can press a button and get 10 air changes per hour for one hour. It totally clears out the house of my smelly cooking!

* Cooling at night in the summer and you can put a summer kit on if you want. During the summer the roof cools down faster than your home so it blows cool air into your bedrooms at night, lowering humidity and making it possible to leave your windows closed - no mosquitos or burglars.

The summer kits take cool air from the south side of the house during the day in summer and blow it through your house.

If you are looking for a ventilation product ask the sales person what the filter filters down to, how many air changes per hour the product gives you and whether they can guarantee positive air pressure if you only have 2 vents. (any one got teenage children who keep the bedroom door closed all the time? How is a vent in the hallway going to keep this room dry and smell free?). Don't forget the guarantee....

This is my two cents worth - as I have said - I have done alot of research before deciding on HRV.

Oh - and if you are turning your HRV off you are doing your house a dis-service by thinking opening the windows is better. The warmer, dryer air in the room cavity and HRV system will give you more air changes than just leaving the windows open - and also - if you want to open the windows you can - just leave the HRV on as well.

Hope this helps save someone some time when deciding which system to install.

[north shore]

hrv comment

We have had an hrv with two motors for about 1.5 years. Had a few problems with HRV, because they are franchises, they don't seem to have the experience that if they were all one company would have to draw on. On the shore they are all young and relatively inexperienced. One of our problems was mould still appearing on an internal bedroom wall, right below the vent! They tried to blame everything on us, e.g: our gas installed in the ceiling space - which is a sealed unit, Rinnai disagreed, our roof leaking, monier disagreed, maybe it was our pipes, plumber disagreed, etc. They had no idea what would be causing it and how to stop it. Ends up the motor wasn't working properly, so they replaced it after we insisted. So we shall wait and see now.
One thing we have found out is on the cold side of the house, if we keep those bedroom doors closed rather than open, it keeps both the hallway they are off and the bedrooms themselves warmer by about two degree's. We have vents in all the bedrooms. HRV didn't know why, they say it shouldn't make any difference.

[rockran]

This is the 2nd winter with the HRV system and so far it's been great. The coldest night had a slight misting on the kitchen/hall windows mostly because the curtains are under a pelmet & I've done some cooking the previous night. If I pull the curtains slightly ajar (which is what the DVS guy said to do for curtains with pelmets) its gone.

Also the guys on the Shore were young but efficient and professional.

[chook]

what is the temperature like in winter?? do you need alternative heating? HRV rep told me temp doesnt drop below 17 degrees, but what if the temp is 5 degrees outside?.

[whitt]

Does it work with tile roofs? I heard these systems are not as effective due to the insulating factor of the heavy tiles. This means the sun does not heat roof sapce like iron roofs do.

[rockran]

The whole heating aspect of this is very minor. During the day it works a bit but not at night or an overcast day, the temperature in the roof is always lower than the house. I have metal tiles so the roof heats up and cools down very quickly. Don't buy this for the heating and yes you do need alternative heating.

[north shore]

I agree with rockran, don't buy this system for heating. We bought it for the ventilation system, we had crying windows. Excellent for that and kinder on your power bill than a dehumidifer. We have a concrete tile roof, so when the roof temp. is higher than inside, it goes constantly till it is the same. We have a flued gas fireplace for heating.
We have a friend who installed the moisture master for the heating aspect, after they got their first power bill they stopped using the heating part because it was so expensive, they use a portable gas heater! and say oh well the moisture master will remove the condensation and moisture caused by the unflued heater.

[nzfrazer]

I bought a place that already had HRV installed and was looking forward to a nice cosy winter - yeah right! I contacted the local HRV salesteam asking how to heat my house and here are their responses:

Me: I have moved into a home that had HRV already installed. Now the weather is colder, I would like to know what options there are to heat the house with the HRV system, thanks.

Reply: We sell a heater called an Elex. It is a slim line heater that can be hung on the wall if so desired. It is very cheap to run for an electric heater (approx 20-22 cents per hour as compared to a 9 fin oil heater approx 65-70 cents per hour), has a thermostat, and a timing system. The model we sell is the 2000w (2kw), and in white only at this stage.

The price for the basic heater is $427.50 incl gst, if you want feet or castors add $33.75 for the feet or $45.00 for the castors.

This heater comes with a 10 year element warranty, and a 5 year warranty on the heater.

Me: So there's no heating system that connects directly into the HRV to provide sufficient warm air when the roof cavity air is not hot enough?

HRV: The only other thing we have that can be hooked up to the HRV is this.....We have whats called an air tempering unit, which isn't really a heater as such, but as its name suggests, warms the air slightly before it comes into your house. This unit can't give out instant heat like say 20 degrees, but it will give the air approx an 5-7 degree rise in temperature.

It really just allows the HRV to function for longer periods over the winter. These are a 1.1 kw unit, and 1 is needed for each fan being run in a house, so they cost somewhere around the region of 25-30 cents per hour to run, for a one fan unit, double that for a 2 fan unit etc. The amount of heat that will come out of an Air Tempering Unit is tiotally dependent on what temperature the weather is at the time.

when the roof temperature is 6 degrees below the house the Air Tempering unit will kick into life and run for an hour, then it will check the temperature again, and continue to run if necessary. Keep in mind though the cost per hour to run, although the system can be turned off, or set to run constantly until the desired temperature is met.

For your house you are looking at $1025.00 including gst and installation.

[cube]

I agree with north_shore - the heating impact of Moisture Master is minimal compared to the additional electricity bill. We have turned our heaters off.

Luckily, this winter, we have had a free supply of firewood!.

Absolutely no condensation, though, and despite all the rain, no additional mold on the ceilings where once there was plenty!

Damp was the main issue we were trying to address, and I suspect that any of the systems will work for that, subject to installation of the vents in the right places.

cube

[chook]

ok sounds like HRV, DVS, etc no good for heating a property, does anyone know a similar type system,or company that IS good for heating a house as well, is it your central heating system that has been around for a while?

[outspoken]

you're best to talk to a heating professional. Or I've heard the Fujitsu website has lots of useful info.

I've also heard that a fully ducted system has an attachment that does exactly what DVS HRV etc do.

HRV, DVS etc work well in Combination with a heating system, be it a log fire, heat pump, gas fire etc.