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Old 01-15-2009, 09:27 AM   #1
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Ventelation control recomendation


Hi and thanks for reading,

I have a Venmar air exchanger HE2.6 and currently control it with a supra control. I like the ability to use the Max setting when I have a lot of people over, however the 20 minutes on 40 minutes off setting is much more then I need for recommended air exchangers. I want to run it more like 5-10 minutes per hour. Is it possible to put a timer in between the 20/40 setting and the venmar to make it run 10minutes per hour instead of 20?

I have an envirazone package installed and thought about connecting it my 8335 zone board. Settings 400-406 on the IAQ stat seem to automatically set the on/off time of the HRV. Would I still be able to force it to constant on max or min setting? Also I think I would have to choose between the min and max settings. Right now the supra control 20/40 uses max speed. If I go to the IAQ stat I think I would probably choose the max setting. Can the IAQ be programed to manually run a certain percentage of time?

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Old 03-06-2009, 06:39 PM   #2
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So I went ahead and connected my HRV to my IAQ 8335 zone board. The vision pro IAQ now runs the HRV 18mins per hour with setting 404 set to 30%. I really want to go a little lower but the setting won't allow that and I don't understand why. The vision pro IAQ also controls the HRV for frost protection and it does a good job reacting to the changes detected by my outdoor temp sensor and lowering the RH to avoid frost on my windows.

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Old 03-07-2009, 05:27 AM   #3
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Ventelation control recomendation


Decrease the number of bedrooms you have it set for.
And or, the sq ft setting.
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Old 03-07-2009, 06:04 PM   #4
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Quote:
Originally Posted by beenthere View Post
Decrease the number of bedrooms you have it set for.
And or, the sq ft setting.
I'm not sure that will help. I asked the contractor that installed my system to ask Honeywell how settings 400-404 work. Honeywell won't talk to homeowners unless its a simple question like, how long is the power cord? I actually needed to know this to plan where I could wire my outlet. What the contractor said was that settings 401-403, bedrooms, sq/ft, cfm, are only used to compute the ASHREA standard and only setting 404 really matters, which based on the calculations of 401-403 will compute a "P" pass or "F" fail based on the percentage selected. The percentage selected relates to the minutes per hour that the HRV will run. So 30% means 18minutes. I have played with settings 401-403 to get it to pass at 30% but that still doesn't change the fact I want to run it somewhere between 15% and 30% which for some reason honeywell doesn't allow.

I know that you are very knowledgeable in the HVAC field and I appreciate your reading my post, but do know if my understanding above is correct?

My other options right now are:
Balance my intake and output to get a lower cfm. I don't really want to do that because then I loose my top setting which I use when company is over.
or
Come up with an elaborate relay/timer scheme to control the Unit to the exact number of minutes per hour that I want it to run. I'm not really interested in going down this route since this is what the IAQ board should allow me to do.
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Old 03-07-2009, 07:11 PM   #5
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Ventelation control recomendation


Your understanding is correct for the most part.

When you lower sq ft, and set it for 30%. 30% becomes a shorter run time, if you don't lower the CFM setting.

You may also want to lie to it. And tell it your ventilation rate is 190CFM if you have it set lower then that.

That will shorten its run time also.
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Old 03-07-2009, 10:10 PM   #6
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Quote:
Originally Posted by beenthere View Post
Your understanding is correct for the most part.

When you lower sq ft, and set it for 30%. 30% becomes a shorter run time, if you don't lower the CFM setting.

You may also want to lie to it. And tell it your ventilation rate is 190CFM if you have it set lower then that.

That will shorten its run time also.
My HRV cfm is 300 and the max that can be specified in the IAQ setup is 190. I'm pretty much off the autopilot that settings 401, 402, and 403 provide through the pass/fail readout on setting 404. Basically I want less than 30% for setting 404 to get less than 18mins per hour.

I think I'm a little confused still . Are you suggesting that I can get less than 30%/18mins an hour out of setting 404 by adjusting settings 401, 402, and 403?

Edit: after reading your post a few more times, I think the part I may be missing is your definition of run time. Are you referring to it in minutes per hour? I thought the 30% number was simply applied to 60 mins per hour to give a number in this case 18mins. 40% would give you 24 mins. I think you suggesting its more complicated than that and if so, I think a simple example would go a long ways for people slow in the brain like me.
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Old 03-08-2009, 07:26 AM   #7
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Ventelation control recomendation


Simple examples, aren't always easy to make, or give.

The 2 times I have talked to Honeywell tech support about it.
I have gotten 2 stories.

1. Its % of an hour.(No reason given for the jump from 36 minutes to continuous if its % of hour, when I brought that up, or why its not just a minute setting instead of % of an hour)
2. Its % of fresh air units total hourly volume to meet sq ft and bedroom requirements.(as in, bring in 30% of max vent intake hourly ability to meet house requirements)

I have 1 customer that tells me his vent system only runs for 10 minutes.
And others have said it runs for 45 minutes.

I have gone back and played with the settings until I got them to work close to what those customers prefered their systems to work like.

On all of them I change, almost every vent setting.
sq ft, bedrooms, and vent CFM rate.

At this, moment, I can't come up with a good example or description.
Of how those settings change run time.

My internal clock, didn't advance yet this morning.
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Old 03-08-2009, 07:32 AM   #8
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Best thing you can do.

Is play with the settings.
And see how much you can change it.

If it doesn't change enough.

You can add a bypass damper to your exhaust line.
So that some of the exhaust air is put back into your duct system, instead of going outside.

If you do this.
You then also add a delay timer, that closes the damper, if it runs for more then X minutes.

That way, when you have a large amount of company over. And you run it continuous, you get full exchange capacity after it runs X (20, 25, 30 minutes, what ever you set it for) amount of time.
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Old 03-08-2009, 11:48 AM   #9
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I think Honeywell's post-sales support could stand for some improvement. Here is my plan. I'm going to borrow a kill-a-watt device from my power company and plug the HRV into it. This device will give me a run time readout. I'll start my monitoring 30%, 40%, and 50% each for a couple of hours to see if the minutes go from 18, 24, 30 per hour. If they don't then the real fun begins and I'll be playing the IAQ game with settings 401, 402, and 403. I hope answer 2 is correct below, because then I can fool the system into getting what I need for ACH.

One more thing to note. Your customers might not have realized that setting 406 could effect their runtime. I believe it should be turned off for this experiment. If it's left on, then it might skew the hourly run time number. Now that the weather has warmed up a little I should be able to get away with having it off for a while so I can do this experiment. It might be a week or so before I figure this out, and I'll post my findings. Thanks for your help and suggestions.
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Old 03-08-2009, 05:20 PM   #10
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Ventelation control recomendation


No problem.

And yea, HW's tech support is lacking in their accuracy.
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Old 03-12-2009, 10:57 AM   #11
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Based on what we know about the accuracy of Honeywell support , we need to take this information with a grain of salt.
This is their response to my questions about Vision Pro IAQ settings 401-404


"Thank you for contacting Honeywell.
The Ventilation on the Vision Pro IAQ cannot be made to run less than 30% per hour.
The feature 0404 cannot be set to go below 30%. The ventilation limit has been designed to be within 30% to 60% which cannot be changed.
Honeywell Customer Care
E317187"

Part of my question was why was it designed this way? And that wasn't answered. I still plan on proving this out myself, just haven't made it to the util company yet to pick up the kill-a-watt measuring device.
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Old 03-12-2009, 01:42 PM   #12
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Wonder why, if its designed to be between 30 and 60%, do they have a 100% setting.
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Old 04-05-2009, 12:28 AM   #13
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I went to my utility company and picked up a kill-a-watt device. Here are the numbers.
First off I made sure that frost control wouldn't alter my runtimes so I disabled it. I also made sure it could ventilate around the clock.

9:52am 11:57pm
14:05 total time plugged in to the kill-a-watt device.
16Watts when off
500Watts when on
2.2KWatts used during ~14 runtime hours

Ignoring the watts consumed when it is off I
came up with a number of 31.24% of the time.
2200/500 = 4.4
4.4/14.08333 = .3124

If I play some games with the numbers and try to subtract/remove the 16Watts it consumes when it's off I come out to around 29% runtime per hour.

I had my IAQ settings at 2 bedrooms, 2200sq/ft, and 195cfm. All three of those settings are no where near the correct numbers. I set setting 404 30 and from my calculations above this means 30% of an hour for runtime which is 18mins.

If you would like me to try a different setting tomorrow I can, but I'm pretty sure this is a Case Closed.
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Old 04-05-2009, 12:40 AM   #14
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One thing I'm considering doing is switching the wires inside the Venmar unit to make the High setting the low setting and the low setting the high setting. I've reviewed the wiring diagram and it looks like it would work. This would allow me to run the unit longer at a lower wattage and would probably increase it's thermal transfer efficiency. I'm going to contact Venmar first to see if I can get them to confirm my wiring change. It's on page 20 of the HE 2.6 manual. Venmar used to have the manual on their website but they took it down. I'll see if I can post a snapshot of it later.
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Old 04-05-2009, 06:05 AM   #15
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If you don't mind. Try setting it to a sq ft of 1500.

If it makes no difference, then % is a fixed hourly setting only.

And thank you for checking and reporting.

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