Honeywell AQ475 Problems

ishmael2k

Hi Scott,

I have come to the conclusion that with my house and system the reset is not going to do much for me.

I am still using it, set to 135º low and 170º high. The sensor (Mounted after the pump, on copper with insulation over it) seems to be approximately 15º off and does not react very quickly at all.

The main reason I left it in was the circulator setup. I like having it start up on a call and the run for a short time after the call is ended.

ishmael2k

Defective supply probe?

Just installed an AQ475 on my WM Cga boiler. Mounted the supply probe on the supply piping, (1½" black) about 18" above the boiler, and wrapped it with 1" fiberglass.

Set the following parameters:

Boiler Low Temp. 140ºf

Boiler High Temp. 180ºf

Outdoor Low 0ºf

This is on an all baseboard system, 4 zones, using the end switches to trigger the AQ475.

Everything seems to work ok except that the boiler does not shut down until the boiler mounted high limit is hit.(200ºf)

This is when the outside temps are in the 35 to 40ºf range.

The boiler will then hit approximately 215ºf according to the thermometer mounted on the side.

I do have a fitting available that I could insert a well into but doubt that it is going to do any good as it is just below where the probe is currently positioned.

Is there any good way to tell if the probe is bad? I really can't switch it with the one from the outside w/o quite a bit of work. (I soldered that ones leads and heat tubed tham also.)

I thought that it might be the thermometer on the boiler but kind of doubt this as it seems to read quite close to the one I have mounted on the return line about 30" from the boiler. (Within 3ºf or so when all I am doing is circulating the water through the boiler and bypass.)

Thanks

Rob

rob_26

I have the same control & the high is around 150F and return is 135 based on 35 f outside. it sounds to me that the first thing is to check the wiring for open or short circuits if wiring is ok replace the supply sensor also do you get any errors when you do a self test sequence

ishmael2k

Those are the figures I was expecting when I installed the unit.

No errors in the self test mode but when I unhook the sensor it does show a fault so the wires seem to be ok.

Thanks for the quick reply.

Larry (from OSHA)

Some thoughts

Greetings,

I have the same unit and you may want to try a few things. First off, turn the low limit down to about 110. I know this sounds too low, but depending on the outside temp, there may not be enough reset curve for the unit to work with. Secondly, with the temp sensor on black pipe, it will react more slowly than if on copper. The whole unit seems to react to supply temp changes rather slowly and if you have only one zone or so running, the boiler will rise in temp faster than the 475 can react. (this is just my opinion from experience) If you can put the sensor in a well, it would be the best place for it as it will have a chance to sense the hottest water. I played with mine for some time before getting it dialed in. Try turning the high limit on the 475 down to 160 and the low limit to 110 and see what happens. Also try moving the outdoor low down to -20 and see what happens. What part of the country are you in?

Good luck and keep tweaking.

Larry (from OSHA)

ishmael2k

> Secondly, with the temp sensor on

> black pipe, it will react more slowly than if on

> copper. The whole unit seems to react to supply

> temp changes rather slowly and if you have only

> one zone or so running, the boiler will rise in

> temp faster than the 475 can react. (this is

> just my opinion from experience)


This is what seems to be happening. It's like the control is stuck in slow motion.

I'll get a well and install the sensor there. I'll also play around with the temp settings as you suggest to see what happens.

I am in West Michigan, about 7 miles from the lake. (As the crow flies.)

Thanks for the quick reply!

Rob

Robert_15

i SET MY OUTSIDE TEMP TO 10F IS MY AVG. OUTSIDE LOW IS 20F HERE ON L.I. NEW YORK Maybe it is set to low

ishmael2k

Design temp for this area is between 4ºf and 6ºf.

Thanks

Rob

ishmael2k

Ok I dialed the AQ475 down to 170/130 and the boiler now shuts down at 190f so it looks like it may just be the location of the sensor.

Going to wait a couple of days to install the well as it requires shutting the system down.

I'll alos try dialing it down some more and see if I can get it to respond the way it should.

Rob

Robert_15

You may just install the supply senser on copper pipe at the tee. i think your right about the steel pipe it seems that if you put it on the copper and rap it with foam pipe cover. that is what i did and it seems to work very well
let me know
Robert

ishmael2k

The nearest copper on my system is about 12" beyond the pump. I am going to move it there and see how well it responds.

Thanks again,

Rob

ishmael2k

Ok, moved the sensor to copper, about 10" downstream from the pump, triple strapped it and insulated with foam.


Now with the limits set to:
High 160f
Low 130f
Outside 0f

The boiler turns off at 180f and turns back on at 135f.

Still does not seem right as the temps were in the 25-30f range last night. Going to pick up a well today and see if that will take care of the problem. (Highly doubting it though...)

Larry (from OSHA)

I think

that you don't have enough differential between the hi limit and the lo limit. At 160 and 130 there isn't enough for the control to work with. Set the lo limit to 100 to see if it starts responding more appropriately. As far at the actual temps that you see it responding at, the supply sensor may not be completely accurate and the response time of the control may have a bit to do with it also. Keep in mind that after the burner shuts down, there will be as much as a ten degree increase in water temp as the water continues to soak up heat from the cast iron. This will be variable depending on how many zones are running at once. When the burner shuts down, does the boiler on indicator on the aq475 shut off? It should. I went through much the same situation as you when I first added this control to my system. It is not as precise as you may expect, but after some time and tweaking, you may find it does work.

Larry (from OSHA)

rob_26

with the high limit set to 160 it should stop at that temp when you installed the supply sensor it says to put it after the first elbow for proper mixing it sounds that it is not sensing the accurate temp is it above the circulator? does your circulator run after the cycle is over?

ishmael2k

> with the high limit set to 160 it should stop at

> that temp when you installed the supply sensor it

> says to put it after the first elbow for proper

> mixing it sounds that it is not sensing the

> accurate temp is it above the circulator?


The sensor is located approximately 10" beyond the circulator. Just past the first elbow.

I agree with the high limit set to 160 it should shut down at no higher than 170 and that's on a design temp day.

Went out today and purchased a Weiss mercury style hot water thermometer. Comes with a nice brass well the correct size for the sensor.

I will be installing it in the 1 1/4 black approximately 4" above the boiler. I'll try the sensor there and if it doesn't help at least I'll have confirmation via the 2nd thermometer as to what temps the boiler is reaching.

> does your circulator run after the cycle is over?



The circulator does run for a short time after the call for heat is done.

Thanks!
Rob

ishmael2k

Even w/o enough differential the high limit should still be the high limit right?

It does not seem to be reading the boiler temps at all accurately, I am going to move it to a brass well (See post below) which has a mercury style thermometer that I can swap out to help get a more accurate idea as to what temps the sensor is reading.

I did change the settings to 160f/120f/-10f so we'll see what happens.

When the burner shuts down, does the boiler on indicator on the aq475 shut off? It should.

It does.

As it turns out we have had a warm spell here today and the boiler has yet to run this afternoon.

It'll be interesting when it does to see what temp it runs the boiler up to.

Thanks for all the help!

Rob

rob_26

Do you have a boiler bypass, maybe you need to adjust it to balance the temp

ishmael2k

> Do you have a boiler bypass, maybe you need to

> adjust it to balance the temp




I have a bypass, don't see how that would affect the reset though. Maybe if the sensor was on the return but as it is on the supply just beyond the pump it should not have any affect.

On a side note I now have it shutting down at 170ºf on a 30ºf day and coming on at 135ºf.

To acheive this I had to set the high at 160ºf, the low at 130ºf and the design at -10ºf.

My LWCO should be here tomorrow and at that time I will add the thermometer and well mentioned above to the system and see what kind of response I get then.

Thanks for all the suggestions to date!

Rob

rob_26

you are right it should not have anty effect just brain storming let me know with the the new probe

ishmael2k

Cold in West MI

OK, it is approximatelt 13ºf here with 30mph+ winds and the living room was not getting up to temp. (69ºf) so I went down to see what was what.

The boiler was shutting down at 165-170ºf and then dropping to 130ºf before kicking back on.

I am beginning to think that the reset is going to hit the driveway bouncing...

Set the parameters to 180ºf high and 145ºf low and will watch the temps closely for the next couple of hours.

Still don't have the indoor sendor in a well (Waiting on my LWCO) but am really beginning to think the unit is defective.

Larry (from OSHA)

cold here too

Ok, lets get some more info. How well is your house insulated, mine is r44. How much baseboard in each room? Is it designed for 180? This will influence how your house responds to the lower boiler temps. Right now mine is cutting out at about 170 and in at 126 or so. The settings are hi limit at 170, low limit at 110, outside temp -20. So the control is not precise in the least, but it does reset although last year it was a little more accurate. I've made some changes to both piping and controls since last winter and the possibility of the control being influenced by what it thinks the supply temp is and 120 volt electrical fields is possible due to some relay and wiring routing. But that's another story. By the way it is 13 degrees here in Minneapolis too.

It is time to take a critical look at the amount of baseboards and insulation. Mine was originally sized for 180 or even a little higher at design, but with lots more insulation added I can get away with lower temps and still heat the house nicely to 70. Hope this helps some.

Larry (from OSHA)

ishmael2k

Ok, my house is an old farmhouse, only insulation is in the bathroom and upstairs bedroom. (Recently re-modeled)All but two of the windows are newer though. By R44 I assume you mean the ceiling, the best I have is R19 in the remodeled bedroom. So no it isn't not very well insulated.

As far as baseboard, it covers all (Yes all) of the exterior walls and approximately 50% of the interior walls. So I have plenty of radiation area. Still from what I have observed today it needs 170ºf+ or so to heat in this type of weather. (I figure wind chill at the -30ºf to -40ºf range.) Which the system was hitting, BUT with it dropping down to 130ºf or so on the low side it was losing ground to fast. It is now set at 180ºf high and 145ºf low and is keeping up fine.

Just doubt that I am going to see any real savings with the reset.

Is there a reset that allows you to manually set your reset curve? This might be my best solution as I could tailor it to my house.

Thanks again for the quick reply.

Rob

Larry (from OSHA)

Rob

Well the good news is that when you add lots of insulation some day, you'll be able to use lower temp water and heat the house nicely. But for now, any reset control may be of questionable value. For comfort, reset when working right is very nice and as far as savings go, I've heard various numbers like 10 to 20%. I think I'm getting about 10% savings myself. For your house, set-back thermostats will give you the most bang for the buck. But remember that ANY savings will not start until the house has dropped to the set-back temp. Lots of discussion about that earlier from Mike T. in Swampeast, MO. Reset controls that have the ability to be tweaked include those from Tekmar and others. Stay warm and happy turkey day.

Larry (from OSHA)

ishmael2k

Larry,

> Well the good news is that when you add lots of

> insulation some day, you'll be able to use lower

> temp water and heat the house nicely. But for

> now, any reset control may be of questionable

> value. For comfort, reset when working right is

> very nice and as far as savings go, I've heard

> various numbers like 10 to 20%. I think I'm

> getting about 10% savings myself. For your

> house, set-back thermostats will give you the

> most bang for the buck. But remember that ANY

> savings will not start until the house has

> dropped to the set-back temp. Lots of discussion

> about that earlier from Mike T. in Swampeast, MO.

> Reset controls that have the ability to be

> tweaked include those from Tekmar and others.

> Stay warm and happy turkey day.

>

> Larry (from

> OSHA)



I hear you on the insulation. Unfortunately I will be limited to R19 in the ceilings upstairs due to height restraints.

I was beginning to think along the same lines

ishmael2k

Larry,

> Well the good news is that when you add lots of

> insulation some day, you'll be able to use lower

> temp water and heat the house nicely. But for

> now, any reset control may be of questionable

> value.


I hear you on the insulation. Unfortunately I will be limited to R19 in the ceilings upstairs due to height restraints.

I was beginning to think along the same lines as to the effectiveness of a reset. I am going to leave it set where it is.

I have digital setback thermostats on all the zones. Going to start tracking usage day by day to see what savings I am getting overall. (I just installed the CGa-4 W-M boiler two weeks ago. It replaced a wide open 1962 American Standard 265k BTU unit that was sending a good amount of the basement heat up the chimney.)

Thanks again, hope you and yours had a great Thanksgiving!

Rob

rob_26

Hi Larry i have the same aq475 with the low setting of 130 that does mean the boiler temp would come on at that setting? ive tried to adjust my settings aswell first 120 low - 180 high seems to keep the temp nice but if i am right the greater the degree difference between the high & low would give a longer cycle time right? or is it the low temp is for warmer days?

Larry (from OSHA)

about the AQ475

Hi Rob,

Your system should operate anywhere between those two settings depending how cold it is outside. Longer burner cycle times are ok as you will have longer cycles of just the circulator running as well. What do you have for emitters? Baseboards, radiators or what. This will also play into how well your system will work with a reset control. If you don't have the instruction manual this link should get you there.

http://customer.honeywell.com/Honeywell/UI/UserControls/ProductCatalog/getliterature.axd?LiteratureID=68-0217.pdf

Larry (from OSHA)

rob_26

Hi larry i do have the manual i have baseboards during a cycle comming from nightime setback how long is the cycle on your boiler? it has been about 20f at night today around 33 f i also set the nightime setback from 8 degress to 2 degress it took a long time for recover how long & what is your settings for night & day also the setting for outside is 10f normal avg. on the coldest day

rob_26

it seems that with it set to 180 high 125 low there is a longer cycle( around 7 TO 11 min.) so i am thinking that lowering the high to 170 and the low to 120 would shorter the time between cycles, after both zones were satisfield, the cycle went off then after 6 min the circulator went off the next call for heat was about 1/2 hour later and then again 6 min the circulator went off does this sound right? this is based on 33f outside temp.

rob_26

it seems that with it set to 180 high 125 low there is a longer cycle( around 7 min.) so i am thinking that lowering the high to 170 and the low to 120 would shorter the time between cycles, after both zones were satisfield, the cycle went off then after 6 min the circulator went off the next call for heat was about 1/2 hour later and then again 7 min the circulator went off does this sound right?

Larry (from OSHA)

setback and reset

are not always the best combination because it takes a long time to recover due to the boiler topping out somewhere less than the 180 it wants to see on a design day. So the burner cuts out at say 160 or so and coasts down to 120 or so and while the baseboards get warm, they don't provide enough btu's to overcome the drop in room temp. If you don't do setback, the system will maintain at whatever you have it set to (68-70) all depending on the rest of the building envelope. The idea here is to improve comfort by providing only the amount of heat that the house is losing thereby minimizing temperature swings. Energy savings are acheived by not heating the water more than needed. If you have a house that has poor insulation, drafty windows, etc. setback will give more savings than reset.

I stopped using setback all together last year because it took too long to recover.

rob_26

your right i did change it to 2 deg. instead of 8 deg. seems alot better. i just turned down the high end to 170 & low to 125 or so. in you house what is the time between cycles? also how long is the burn cycle and your temp outside?

rob_26

so you dont setback at all at night?i go down to 65 at night then back up to 69 upstairs. then downstairs is 66 at night then 70 do you think leaving it at say 70 with a 2 deg. setback would be better?

Larry (from OSHA)

like so many things

it depends. A lower amount of setback as you noted will recover better but you must remember that you don't start saving until the house reaches the setback temp. All the time that it coasts down to the lower temp is not saving even though the boiler is off the whole time. You spend it when you recover in the morning. There has been much discussion here on this in the past.

rob_26

So you dont change the settings on th AQ with the season change? so do you think i should set my AQ to 170 high 120 low or some other?

Larry (from OSHA)

I think you are missing the point

Ideally, reset will allow you to not need to make any adjustments of high or low limits over the season. You want to set the high limit at the design temp, most likely about 180 and the low to as low as you can without being too low. For your baseboard system, somewhere about 110 or 120 should not cause problems with condensation due to both the way the AQ475 works and the amount of time that the boiler will actually see low return temps. (some tweaking may be needed).

The control will adjust the temp that the boiler operates at depending on the outside temps, so you should not need to readjust those limits. However, the outside temp adjustment is where you can tune it. As an example, the design temp here in Minneapolis is -16 and my control is set somewhere around -30.

Hope this helps.

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rob_26

thanks larry

rob_26

Hi Larry when you measure the low temp is that of the boiler termomoter or the return from the zones, or the supply?

Robert_15

Hi rob I was wondering how that supply sencor worked out? is the aq working with it in the well

Robert_15

Hey rob I have the same issue the only differce is that the plumber set the boiler high limit to 180 so the boiler would shut down, now i put it up to 200 that is where the boiler shuts down. thay also had the dhw switch to circulator not valve. not all plumbers know how to set these devices, i had to figure this out. i do think there is a problem with the aq i am going to have them replace it and put the supply sencor on the supply end really close to the boiler outlet on black pipe and see if works better. i did menthod they should mount the supply in the shell but we can't gat in the burnham shell.
so how did yours work out?
Thanks