Just no Hoval ventilation unit!!!
For anyone planning to install a heat recovery ventilation system, I can only advise against the Hoval unit! Unfortunately, we have one installed in our basement and have had nothing but problems. The first unit was replaced by customer service after the first winter because condensate water in the rotary heat exchanger froze at low temperatures. So, a new unit was installed, which runs noticeably quieter than the old one (though it’s still audible). However, almost all problems persist. The system was planned and installed by Hoval, but unfortunately, the location in the unheated storage area turned out to be very unsuitable—there were significant energy losses due to uninsulated piping. We had to cover the entire insulation cost ourselves.
I haven’t even mentioned the most serious issues yet. At lower temperatures, which can drop to minus 24 degrees Celsius (minus 11°F) where we live, the supply air temperature only reaches about 8-9 degrees Celsius (46-48°F), despite the promised 17 degrees Celsius (63°F). Because we don’t live in a mild climate like Italy, the supply air needs preheating regardless of the system used. Hoval still insists their system works without preheating. Furthermore, there is excessive moisture in the living space due to moisture recovery. At lower temperatures, the rotor speed is increased counterproductively, leading to window condensation at a relative humidity of 40-50%.
The worst part is the spread of odors and noise throughout the house. Since all exhaust air from the entire house comes into contact with the supply air in the rotary heat exchanger, the entire home ends up smelling like cooking odors or, even worse, toilet odors. Exhaust and supply air systems must be kept separate!!!
All attempts to get a response from Hoval have so far been unsuccessful.
For anyone planning to install a heat recovery ventilation system, I can only advise against the Hoval unit! Unfortunately, we have one installed in our basement and have had nothing but problems. The first unit was replaced by customer service after the first winter because condensate water in the rotary heat exchanger froze at low temperatures. So, a new unit was installed, which runs noticeably quieter than the old one (though it’s still audible). However, almost all problems persist. The system was planned and installed by Hoval, but unfortunately, the location in the unheated storage area turned out to be very unsuitable—there were significant energy losses due to uninsulated piping. We had to cover the entire insulation cost ourselves.
I haven’t even mentioned the most serious issues yet. At lower temperatures, which can drop to minus 24 degrees Celsius (minus 11°F) where we live, the supply air temperature only reaches about 8-9 degrees Celsius (46-48°F), despite the promised 17 degrees Celsius (63°F). Because we don’t live in a mild climate like Italy, the supply air needs preheating regardless of the system used. Hoval still insists their system works without preheating. Furthermore, there is excessive moisture in the living space due to moisture recovery. At lower temperatures, the rotor speed is increased counterproductively, leading to window condensation at a relative humidity of 40-50%.
The worst part is the spread of odors and noise throughout the house. Since all exhaust air from the entire house comes into contact with the supply air in the rotary heat exchanger, the entire home ends up smelling like cooking odors or, even worse, toilet odors. Exhaust and supply air systems must be kept separate!!!
All attempts to get a response from Hoval have so far been unsuccessful.
1. I have had a Hoval Homevent 250 since 2005 and am very satisfied. I chose it over comparable offers with a ground heat exchanger. The only modification I made was adding additional silencers both to the rooms and to the outside (due to a very sensitive neighbor). The air re-humidification works very well. Odor transfer – none.
I am currently experiencing a malfunction and have done some research, which led me to this post.
2. Regarding the G4 filter: Martin 206, do you install the filter outdoors? What material did you use to sew the bag? I don’t see any seams in the picture. I would appreciate more information. Where did you buy the G4 filter bag?
3. I find the idea of "self-made" filters inside the unit very interesting. Has anyone here tried this before?
I am currently experiencing a malfunction and have done some research, which led me to this post.
2. Regarding the G4 filter: Martin 206, do you install the filter outdoors? What material did you use to sew the bag? I don’t see any seams in the picture. I would appreciate more information. Where did you buy the G4 filter bag?
3. I find the idea of "self-made" filters inside the unit very interesting. Has anyone here tried this before?
M
Martin20610 May 2016 21:32Sorry, I don’t check here regularly.
What kind of malfunction? Only the LED light is red? Or are there noises coming from the rotor?
Your 2005 model might have been delivered with the less durable bearings...
Regarding point 2:
Until this year, my supply air duct ended in the shed (at the carport). I simply inserted it into the pipe, pulled it over the edge, and put the end piece with insect screen back on.
The filter is simply sewn from G4 filter fabric sold by the meter. I buy it where it’s cheapest. Ideally about 20mm (0.8 inches) thick, with a progressive structure and an Ökotex label or other certification indicating it’s free from harmful substances. (Search on Ebay: Filter G4 progressive)
Yes, just sewn. I calculated the circumference using the circle formula from the diameter:
3.14 × diameter, so for a 200mm (8 inch) pipe that’s 62.8cm (24.7 inches) + about 1cm (0.4 inches) for the seam.
I cut 1m (39 inches) by 64cm (25 inches), sewed the long and one short side, and that’s it.
Regarding point 3:
I wouldn’t recommend a homemade filter inside the unit.
These parts are available from independent suppliers online for free or around €30 including shipping.
Filter fabric by the meter won’t work inside the unit.
But you can sew something from it yourself for valve filters and for the fresh air intake outside.
link removed by moderator; Building Expert
Regards,
-Martin-
What kind of malfunction? Only the LED light is red? Or are there noises coming from the rotor?
Your 2005 model might have been delivered with the less durable bearings...
Regarding point 2:
Until this year, my supply air duct ended in the shed (at the carport). I simply inserted it into the pipe, pulled it over the edge, and put the end piece with insect screen back on.
The filter is simply sewn from G4 filter fabric sold by the meter. I buy it where it’s cheapest. Ideally about 20mm (0.8 inches) thick, with a progressive structure and an Ökotex label or other certification indicating it’s free from harmful substances. (Search on Ebay: Filter G4 progressive)
Yes, just sewn. I calculated the circumference using the circle formula from the diameter:
3.14 × diameter, so for a 200mm (8 inch) pipe that’s 62.8cm (24.7 inches) + about 1cm (0.4 inches) for the seam.
I cut 1m (39 inches) by 64cm (25 inches), sewed the long and one short side, and that’s it.
Regarding point 3:
I wouldn’t recommend a homemade filter inside the unit.
These parts are available from independent suppliers online for free or around €30 including shipping.
Filter fabric by the meter won’t work inside the unit.
But you can sew something from it yourself for valve filters and for the fresh air intake outside.
link removed by moderator; Building Expert
Regards,
-Martin-
Thanks, Martin!
I have now received a quote from Hoval: material costs around 1000€ with a 10% goodwill discount since the unit is already quite old. However, no one from Hoval ever told me there was a goodwill period that expires, during which it would still make sense to replace the rotor.
Fortunately, a Hoval technician told me that if you’re reasonably handy, you can open the unit yourself. You just have to be careful not to tear the cable when pulling out the rotor.
The unit is really easy to open. I also took some documentary photos in case anyone is interested. The bearings are in good condition. You could even swap the two upper bearings with the lower ones, as the upper ones are barely loaded, but that wasn’t necessary. The rotor didn’t spin because the motor that turns the rotor is broken.
I have already requested a quote from Hoval for the motor but haven’t received an offer yet.
Being curious, I bought a DC gear motor from Neuhold Electronics for about 10€. The drive gear fits well. I then installed the motor with a temporary mounting and powered it with my lab power supply.
And it works!!!
In the first few days, the system showed an orange warning light roughly once a day. Now it’s running for five days without any problem. I suspect the Teflon lip seal still needs to be replaced.
I’ll run a continuous test for about a month and then decide whether to install a fixed speed controller on the unit (these cost just a few euros on Amazon).
I think I can live with some fluctuations in relative humidity. For me, the important thing is that the rotor actually turns, as this prevents the air from drying out.
Best regards,
Dominik
I have now received a quote from Hoval: material costs around 1000€ with a 10% goodwill discount since the unit is already quite old. However, no one from Hoval ever told me there was a goodwill period that expires, during which it would still make sense to replace the rotor.
Fortunately, a Hoval technician told me that if you’re reasonably handy, you can open the unit yourself. You just have to be careful not to tear the cable when pulling out the rotor.
The unit is really easy to open. I also took some documentary photos in case anyone is interested. The bearings are in good condition. You could even swap the two upper bearings with the lower ones, as the upper ones are barely loaded, but that wasn’t necessary. The rotor didn’t spin because the motor that turns the rotor is broken.
I have already requested a quote from Hoval for the motor but haven’t received an offer yet.
Being curious, I bought a DC gear motor from Neuhold Electronics for about 10€. The drive gear fits well. I then installed the motor with a temporary mounting and powered it with my lab power supply.
And it works!!!
In the first few days, the system showed an orange warning light roughly once a day. Now it’s running for five days without any problem. I suspect the Teflon lip seal still needs to be replaced.
I’ll run a continuous test for about a month and then decide whether to install a fixed speed controller on the unit (these cost just a few euros on Amazon).
I think I can live with some fluctuations in relative humidity. For me, the important thing is that the rotor actually turns, as this prevents the air from drying out.
Best regards,
Dominik
M
Martin20611 May 2016 21:57I was supposed to pay 1,070 EUR (for a rotor replacement) ...then I happened to meet a senior Hoval employee online who said it should be covered as a goodwill gesture.
The invoice and reminder arrived ...only after he inquired again was the invoice canceled and I was informed that Hoval would cover the entire cost.
Apparently, this is not the usual procedure... :eek
Yes, the unit can be easily opened and is quite accessible from the inside.
Is the motor really broken? Or could it be its control system?
If it’s the motor, I would install an equivalent replacement here (possibly as a spare part from Hoval—if not hopelessly overpriced).
The rotor control is certainly done for various purposes, including preventing icing in winter. Possibly also to avoid excessive humidity inside the unit?
Potential consequential damage could certainly be expected here.
Regards
-Martin-
The invoice and reminder arrived ...only after he inquired again was the invoice canceled and I was informed that Hoval would cover the entire cost.
Apparently, this is not the usual procedure... :eek
Yes, the unit can be easily opened and is quite accessible from the inside.
Is the motor really broken? Or could it be its control system?
If it’s the motor, I would install an equivalent replacement here (possibly as a spare part from Hoval—if not hopelessly overpriced).
The rotor control is certainly done for various purposes, including preventing icing in winter. Possibly also to avoid excessive humidity inside the unit?
Potential consequential damage could certainly be expected here.
Regards
-Martin-
Unfortunately, we also have one of those HOVAL units in use. So far, we've apparently been lucky with the rotary heat exchanger. I think the ground heat exchanger with a pre-filter installed upstream helps us somewhat as well. However, we keep having issues with the fan motors. Now it's that time again—we are expected to pay over €360 for a new fan (without installation). Hoval really charges a premium for their parts.
One more comment on the humidity recovery: it doesn’t work for us at all. No matter how the settings on the control panel are adjusted, the relative humidity always drops sharply in winter. Only by using several powerful room humidifiers are we able to raise the relative humidity to around 40%.
For our next house, or if this unit fails completely, we will definitely not buy a Hoval device again.
One more comment on the humidity recovery: it doesn’t work for us at all. No matter how the settings on the control panel are adjusted, the relative humidity always drops sharply in winter. Only by using several powerful room humidifiers are we able to raise the relative humidity to around 40%.
For our next house, or if this unit fails completely, we will definitely not buy a Hoval device again.
So, now the drive motor of our heat exchanger is also broken. The motor has a bearing failure and is constantly jerking and rattling. I’ve asked Hoval for the price of a replacement part. I’m curious to see what they will say...
For the next house build, Hoval is definitely out...
For the next house build, Hoval is definitely out...
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