Recommend cheap ventilation system to replace failed motor in current one

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timmmay

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#247809 24-Feb-2019 13:15

The previous owner put a cheap Drivaire positive pressure ventilation system into the house. It's lasted about 15 years, which is pretty good, but it seems to have failed.

We only need something simple. I take fresh air from under the eaves, the motor pushes it outlets into the kitchen and hallway. It doesn't even have a filter, it used to have a sock filter but I removed it when I changed intake from ceiling cavity to eaves. It's on a cheap $10 timer from Miter Ten, running morning and evening in summer and during the day in winter. It's just to avoid opening windows really. We don't need smarts, just a motor.

I've asked Drivaire for a quote to replace the motor or the whole unit, but also interested in other options. Ideally replacing only the motor / control system.

I did consider replacing it with a fancy heat exchange unit, but don't want to spend $5K right now. Don't really need one.

I don't want to do anything myself, I have a shoulder injury that prevents me doing the work.

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#2186269 24-Feb-2019 13:19

Just get an extractor fan (the in duct type) and use that. Get a Mixed flow or Centrifugal type. As they work much better on longer ducting than propeller style fans.

timmmay

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#2186272 24-Feb-2019 13:23

I don't want to do anything myself, I have a shoulder injury that prevents me doing the work.

A simple fan would work fine @aredwood. Where would a source a nice quiet one that would fit in the existing thingy?

I'll update the original post with a couple of pictures.

Aredwood

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#2186275 24-Feb-2019 13:30

Ask your Electrician As they can get some grunty fans through the electrical wholesalers.

Also, if you want to make the system “smart” Consider getting a fan that uses a 3 phase motor. And using a Variable speed Drive with it. As pretty much all VSDs seem to support RS 422 or other communications protocols, that would make controlling them from a home automation system easy.

timmmay

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#2186278 24-Feb-2019 13:39

Thanks :) I don't much care about home automation. The cheap timer works fine for basic automation. I'll ask my electrician, thanks. Just need something fairly quiet.

I'll see with Drivaire says as well. Any other suggestions welcome.

Kickinbac

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#2186359 24-Feb-2019 14:40

Aredwood: Ask your Electrician As they can get some grunty fans through the electrical wholesalers.

Also, if you want to make the system “smart” Consider getting a fan that uses a 3 phase motor. And using a Variable speed Drive with it. As pretty much all VSDs seem to support RS 422 or other communications protocols, that would make controlling them from a home automation system easy.

Most houses don’t have 3 phase power. A simple dimmer type fan speed controller would work but don’t think thats what the OP wanted.

Kickinbac

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#2186361 24-Feb-2019 14:44

timmmay:
Thanks :) I don't much care about home automation. The cheap timer works fine for basic automation. I'll ask my electrician, thanks. Just need something fairly quiet.

I'll see with Drivaire says as well. Any other suggestions welcome.

For a suitable fan, contact a local aiconditioning company or fan supplier. Selecting a suitable fan requires some skill/knowledge as you need to know the aiflow and pressure drop to do the job and then select a fan that can do this and is quiet.
Maybe try venttech.co.nz they are in Lower Hutt. They sell fans and may be able to direct you to a good local company.

sparkz25

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#2186369 24-Feb-2019 15:01

As @aredwood has mentioned get a mixed flow like this one http://simx.co.nz/product-groups/extraction-fans/inline-fans/manrose-pro-series-inline-mixed-flow-fans

There are usually a few options for wiring these in, so you can get you sparky to install a 4 pos switch so you can have it on high medium or low or just pick a setting and leave it.

Wiring Diagram/installation instructions http://simx.co.nz/images/uploads/resources/Mixflo_Fan_MF.pdf

It also looks like you have insulated ducting so that will take alot/all of the fan noise out, I would also remove the chain and replace it with a bungee cord to absorb the vibrations for the mixed flow fan as they do move a-lot of air and can make a bit of noise if they are screwed to timber.

I have one of these pulling cool air from under the house in to my server cupboard through a washable filter cooling my server and then in to the ceiling through some insulated ducting and back in to the hallway and you cant even hear the fan running.

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Aredwood

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#2186371 24-Feb-2019 15:24

Kickinbac:
Aredwood: Ask your Electrician As they can get some grunty fans through the electrical wholesalers.

Also, if you want to make the system “smart” Consider getting a fan that uses a 3 phase motor. And using a Variable speed Drive with it. As pretty much all VSDs seem to support RS 422 or other communications protocols, that would make controlling them from a home automation system easy.

Most houses don’t have 3 phase power. A simple dimmer type fan speed controller would work but don’t think thats what the OP wanted.

Which is why I suggested using a VSD. As a VSD allows you to run 3 phase motors from single phase power.

And not all single phase motors will work properly from dimmer type controllers. Often the motor puts out hardly any power, and then overheats. And often speed regulation is poor as well using such controllers.

Sure, a 3 phase motor with a VSD wont be the cheapest system. But if stepless speed control is needed. It is definitely the best system.

And since this is a geek forum. It should be expected that geeky solutions would be proposed.

timmmay

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#2186430 24-Feb-2019 17:36

My electrician wants to sell me a SmartVent system. Not sure I want the expense, but will see what it'll cost. He didn't seem keen on putting in just a new fan motor.

We don't need a really powerful motor. It just needs to suck in air through about 4m of duct, then blow it out through 2m + 4m ducts. We don't need the crazy 3-4 air changes per hour, just a bit of ventilation. I'd run it on the lowest speed most likely.

Will look a bungee to replace chains, but bungee tend to wear out, chain not so much. Might be an option if it's noisy. Honestly if it's annoying when we're home I'll just have it run when we're not here, it doesn't need to run at night when we're in bed for example.

Thanks for the really specific advice @sparkz25, and @Kickinbac yeah I've been in there before, might be able to pop in there.

Hopefully drivaire can just replace the fan or do a cheap upgrade.

Kickinbac

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#2186434 24-Feb-2019 17:45

Aredwood:
Kickinbac:
Aredwood: Ask your Electrician As they can get some grunty fans through the electrical wholesalers.

Also, if you want to make the system “smart” Consider getting a fan that uses a 3 phase motor. And using a Variable speed Drive with it. As pretty much all VSDs seem to support RS 422 or other communications protocols, that would make controlling them from a home automation system easy.

Most houses don’t have 3 phase power. A simple dimmer type fan speed controller would work but don’t think thats what the OP wanted.

Which is why I suggested using a VSD. As a VSD allows you to run 3 phase motors from single phase power.

And not all single phase motors will work properly from dimmer type controllers. Often the motor puts out hardly any power, and then overheats. And often speed regulation is poor as well using such controllers.

Sure, a 3 phase motor with a VSD wont be the cheapest system. But if stepless speed control is needed. It is definitely the best system.

And since this is a geek forum. It should be expected that geeky solutions would be proposed.

A three phase fan + vsd not necessarily the best solution. For a geeky solution in this case and in my opinion an EC fan would be best.
For example a modern single phase EC fan would offer the same result for a lot less complication in a size to suit, I was reckoning on about 150 L/s for Timmay’s house. An EC fan works on similar principal as a smart drive motor. An EC fan has a built in variable speed controller and motor protection and uses a 0-10v signal to control speed, 0v = off, 10v = 100%. This can be done with a trim pot or external controller so saves the cost and complication of a VSD. Plus they are energy efficient.
Something like this... https://www.fantech.com.au/FanRange.aspx?EnergyEff=Y&RangeID=224&Ecowatt%20Series for a small fan.
But this would be a more expensive solution to a single phase fan with a dimmer type speed controller.
For commercial buildings we regularly use an air quality sensor, measuring CO2 that outputs 0-10v signal direct to run an EC ventilation fan, usually a small inline mixed flow fan. This means fans ramp up and down as necessary to maintain air quality, more often reducing the heating and cooling load of the fresh air on the air conditioning systems.
3 phase fans and VSD’s have their place but only once getting way beyond air volumes required in a house!

timmmay

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#2186492 24-Feb-2019 20:30

Kickinbac:

A three phase fan + vsd not necessarily the best solution. For a geeky solution in this case and in my opinion an EC fan would be best.
For example a modern single phase EC fan would offer the same result for a lot less complication in a size to suit, I was reckoning on about 150 L/s for Timmay’s house. An EC fan works on similar principal as a smart drive motor. An EC fan has a built in variable speed controller and motor protection and uses a 0-10v signal to control speed, 0v = off, 10v = 100%. This can be done with a trim pot or external controller so saves the cost and complication of a VSD. Plus they are energy efficient.
Something like this... https://www.fantech.com.au/FanRange.aspx?EnergyEff=Y&RangeID=224&Ecowatt%20Series for a small fan.
But this would be a more expensive solution to a single phase fan with a dimmer type speed controller.
For commercial buildings we regularly use an air quality sensor, measuring CO2 that outputs 0-10v signal direct to run an EC ventilation fan, usually a small inline mixed flow fan. This means fans ramp up and down as necessary to maintain air quality, more often reducing the heating and cooling load of the fresh air on the air conditioning systems.
3 phase fans and VSD’s have their place but only once getting way beyond air volumes required in a house!

Seems like a nice system for commercial. At home we just pump a bit of fresh air in at about the right time of day to warm it up or cool it down, given windows are sometimes open too it's convenient rather than necessary. Problem we have right now is the house painters have covered all the windows with plastic so we have no ventilation at all! Can't even open the doors because our toddler would escape!

eph

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#2186501 24-Feb-2019 21:09

I've recently faced the same problem. My old SmartVent fan died I was looking for replacement - I've tried to deal with SmartVent previously but their sale system is ridiculous - you have to waste money for the privilege of having to go to some expensive (unless you've got account and buy lots of stuff) electrical retailer and sort everything through them. In the end I just bought a fan from MingFans - yes Chinese importer but I've dealt with them in the past when I was looking for motorised damper (for the SmartVent again) - which still works. I can only say the fan is much quieter and the build quality seems much better than the old fan as well.

Btw. I've noticed that they've started selling PP systems as well when I was looking for the fan...

timmmay

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#2186619 25-Feb-2019 07:24

eph:

I've recently faced the same problem. My old SmartVent fan died I was looking for replacement - I've tried to deal with SmartVent previously but their sale system is ridiculous - you have to waste money for the privilege of having to go to some expensive (unless you've got account and buy lots of stuff) electrical retailer and sort everything through them. In the end I just bought a fan from MingFans - yes Chinese importer but I've dealt with them in the past when I was looking for motorised damper (for the SmartVent again) - which still works. I can only say the fan is much quieter and the build quality seems much better than the old fan as well.

Btw. I've noticed that they've started selling PP systems as well when I was looking for the fan...

Thanks, that's really useful that @eph :-)

I've asked for a price for their ventilation system, I like that it would have a filter.

This fan looks like it could be a simple drop in replacement for the current system. It comes with a switch so I can choose 500 - 800 cubic meters per hour, and I could just have it wired to the mains timer. I could remove all the current guff that came with the current system, like the thermostat that turns it off when the roof cavity gets hot, which is pointless given we take air from the outside.

I guess I'll see what the vendors come back with before I decide on new ventilation system vs just replace the fan.

nickb800

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#2186634 25-Feb-2019 07:53

Given that you say it plugs into a Mitre10 timer, I presume the current fan simply plugs in? Rather than hard-wired? In which case, a competent handy man could do this for you (which may avoid upselling electricians)

timmmay

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#2186637 25-Feb-2019 07:56

nickb800:

Given that you say it plugs into a Mitre10 timer, I presume the current fan simply plugs in? Rather than hard-wired? In which case, a competent handy man could do this for you (which may avoid upselling electricians)

Currently the fan plugs into a controller box which AFAIK is just a thermostat, the controller box plugs into a standard mains plug. I don't know why it's not hard wired, but it's useful this way because I can control it with a $10 timer.

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