I get by with help from my friends.

EBEBRATT-Ed

I'll be the electrical inspector. Sealtight needs to be supported below disconnect. I don't see the low voltage. If it's pulled in with the power it should be 600 volt wire like the power wires.

everything you do is top notch. I'm just being picky

ChrisJ

> @EBEBRATT-Ed said:
> I'll be the electrical inspector. Sealtight needs to be supported below disconnect. I don't see the low voltage. If it's pulled in with the power it should be 600 volt wire like the power wires.
>
> everything you do is top notch. I'm just being picky

Funny you should mention that.
Just after we got done putting the lineset cover up @njtommy said "did you remember the low volt wire?"

Dammit!

I was able to fish it about half way down, but need to pull some covers off when it stops raining.

ratio

ChrisJ

> @EBEBRATT-Ed said:
> I'll be the electrical inspector. Sealtight needs to be supported below disconnect. I don't see the low voltage. If it's pulled in with the power it should be 600 volt wire like the power wires.
>
> everything you do is top notch. I'm just being picky

@EBEBRATT-Ed Speaking of this.
I finally got the wire pulled last night. I'm using a good heavy 18/4 wire rated for 300V. My outdoor unit has a small enclosed metal box for the low voltage wire, which then has a few wires run into it from a terminal block on the PCB. I assume this was done to keep the typical low voltage wire away from high voltage stuff.

Being my wire is rated for 300V can I go ahead and remove their short pigtails and run my wire right to the terminal block?

I mean, I know I can. But can I legally?

ChrisJ

Here's the latest duct drawing.

It's pretty accurate to what actually happened. All of the return grills are expected to end up with Koch 1" fiberglass prefilters due to their super low pressure drop when new. The Airbear is tarting with a MERV 8 but may go to a MERV 11 depending on static pressure.





The curved pieces of flex were done solely for acoustic reasons. I could've much easier just done short runs of hard pipe.

ChrisJ

@Rich Thoughts?

I know the ductwork could be better. I did the best I could with what I've got.

ChrisJ

@Gordy
97° yesterday, a record high for the area and the system ran in high stage almost the entire day. Indoor temp was reasonable, though a little above setpoint.

94° system will maintain setpoint, but will run in high stage the entire time. If you recall, we did the heatgain for 95°.

Sizing is about spot on, although our hallway area upstairs certainly wasn't as expected and I'm not entirely sure why. This called for something along the lines of 80 CFM. I'm feeding it 150-160 CFM and it's several degrees (4+) above the est of the house. This morning, the first floor was 2 degrees warmer and I noticed as soon as I started the system, that area warmed 2 degrees rather fast. I suspect it's because I'm using the area as the return for the first floor, so all of the heat is ending up there.

No biggie.

3 tons isn't oversized. It's perfect.

I have a remote sensor for the VP8000 coming because it is in that warmer area, and is messing everything up. At night, that area cools off, so the rest of the house ends up warm. During the day like now, it's 4+ degrees warmer. The remote sensor will allow me to mess around and see what I feel works best.

JUGHNE

I just raised my T-stat to 76 as the cool air is annoying with the setting at 74. My wife's end of the house unit is set at 74, which is nice for sleeping. My RH is 46-48%.
Just curious of your indoor temp and RH. Actually a general survey of how people acclimatize to AC.
I spent the day in a boiler room that was 85-90 (actually cool with the steamers off ). So the 75 or so seems really cool.

In our new (100 YO building) movie theater I put the remote sensors in the return just ahead of the Air Bears, we have 3 units.
The T-stats are in a mech closet. (The disadvantage to the closet is that is the RH it samples, so the closet door is open when there are no movies showing) We run the blowers constantly. They are variable speed and when no call for heat or cool they run at 1/2 speed. This seemed an easy way to sense temp. We have a good solar gain with a west showcase window and try to even temps out in the main seating area. FWIW

ChrisJ

JUGHNE said:

I just raised my T-stat to 76 as the cool air is annoying with the setting at 74. My wife's end of the house unit is set at 74, which is nice for sleeping. My RH is 46-48%.
Just curious of your indoor temp and RH. Actually a general survey of how people acclimatize to AC.
I spent the day in a boiler room that was 85-90 (actually cool with the steamers off ). So the 75 or so seems really cool.

In our new (100 YO building) movie theater I put the remote sensors in the return just ahead of the Air Bears, we have 3 units.
The T-stats are in a mech closet. (The disadvantage to the closet is that is the RH it samples, so the closet door is open when there are no movies showing) We run the blowers constantly. They are variable speed and when no call for heat or cool they run at 1/2 speed. This seemed an easy way to sense temp. We have a good solar gain with a west showcase window and try to even temps out in the main seating area. FWIW

Depends on who (which sensor) you ask.
Some read mid to high 40s, others low 50s.

Right now, I can't slow my blower down until we figure out the TXV issue, if that's what it is.

Aren't you concerned about blowing moisture back into the conditioned space having the blowers run all of the time?

JUGHNE

I have heard that mentioned before and reminds me to check T-stat settings of delayed off fan operation, should be set to zero run on after time.
But the 2 main units that heat and cool the building are only 2 tons each. So when the cool is off the blower really slows down. (they are up flow HP over gas FAF if that matters.) We have a dedicated AC only 4 ton (VB also) unit that has attic ductwork with ceiling diffusers. This is all sized for 100 people, my best guess by the way. We have only 67 seats. Most people bring a sweater to the movies.

Gordy

What's your setpoint?

Harvey Ramer

What symptoms are you seeing with the txv?

njtommy

@Harvey Ramer txv is hunting and not settling down. I feel it's a txv bulb placement issue. Bulb is before the equalizer from factory and is way to close to evap collection header. Bulb I feel should be out side of the cabinet and heavily insulated. It will give better response in my opinion. Amana is after some pretty tight tolerance with 7-9 superheat and 6-8 subcooling.

Harvey Ramer

Sounds like you might be right. Since the bulb was mounted from the factory and the airhandler is in a horizontal position, is the bulb still in the correct orientation? Acting as a resivor and not reading oil temp on the inside of the pipe?

ChrisJ

> @Harvey Ramer said:
> Sounds like you might be right. Since the bulb was mounted from the factory and the airhandler is in a horizontal position, is the bulb still in the correct orientation? Acting as a resivor and not reading oil temp on the inside of the pipe?
>

Here's a picture I took before I insulated it. I also insulated the strap and piping before and after.

ChrisJ

Harvey Ramer

What's the subcooling at the at the evap? It may have to be increased at the condenser unit to account for the lift to the attic. Do you have a sight glass in the attic? If you have saturated liquid hitting the txv, it will hunt. Guaranteed.
Looks like you have the bulb correctly mounted.

ChrisJ

Harvey Ramer said:

What's the subcooling at the at the evap? It may have to be increased at the condenser unit to account for the lift to the attic. Do you have a sight glass in the attic? If you have saturated liquid hitting the txv, it will hunt. Guaranteed.

Looks like you have the bulb correctly mounted.

Sight glass about 24" before TXV. No bubbles.

This was also the reason I added around 1 pound 6 ounces the second time I ran it. I figured there must be gas getting to the TXV and decided to add refrigerant. At one point, I said screw it, and added quite a bit just to see what direction it would go in. The problem was the same, just with much higher pressure.

I'm fairly confident there's a solid column of liquid at the TXV.

Harvey Ramer

How wide is the superheat swing of the txv?
That does sound strange.
Is your air flow stable across the evap?
I have never seen a bad txv out of the box. No obstruction in the equalizer tube?

Harvey Ramer

Also gusting winds across the condenser coil can cause what appears as a hunting txv.

ChrisJ

Harvey Ramer said:

How wide is the superheat swing of the txv?

That does sound strange.

Is your air flow stable across the evap?

I have never seen a bad txv out of the box. No obstruction in the equalizer tube?

As far as I know the airflow is stable, the static pressure is reasonably stable. Didn't pull the equalizer off, but there's no kinks or anything in it. It was installed by the factory.

Here's it's behavior from last night. No temps shown, but it'll give an idea of what the pressures are doing now. With my equipment, I have no easy way of showing the moving SH and SC temps.


https://youtu.be/DzocuMNVdlw

Harvey Ramer

What size is the tubing that the bulb is on?
Up to 3/4" should be mounted at 12:00. 7/8" and up should be mounted at 2:00. Needs to be mounted away from any location that is prone to having oil directly on the inside wall of the pipe where the bulb makes contact. This can be tricky if the bulb is mounted right after a bend in the pipe, as the velocity of the refrigerant can propel the oil to the top and high sidewalls of the outside of the bend. If I have to go right after a bend, I tend to favor the inside of the bend as a mounting location.

The bulb also has to be tightly mounted for optimal contact. I prefer 2 straps tightened with screws.

ratio

@Harvey Ramer, ever use a heat transfer aid of any sort, like computer heat sink compound, or Heat Conductive Compound? I'm curious if it would be of any benefit.

ChrisJ

> @Harvey Ramer said:
> What size is the tubing that the bulb is on?
> Up to 3/4" should be mounted at 12:00. 7/8" and up should be mounted at 2:00. Needs to be mounted away from any location that is prone to having oil directly on the inside wall of the pipe where the bulb makes contact. This can be tricky if the bulb is mounted right after a bend in the pipe, as the velocity of the refrigerant can propel the oil to the top and high sidewalls of the outside of the bend. If I have to go right after a bend, I tend to favor the inside of the bend as a mounting location.
>
> The bulb also has to be tightly mounted for optimal contact. I prefer 2 straps tightened with screws.

It's 7/8.

Do you think moving the bulb a few inches outside the cabinet and insulating the hell out of it would cure the hunting? Should get it away from any oil as well.

What do you think?

Harvey Ramer

@ratio I imagine it wouldn't hurt if it doesn't get wet. That's some messy stuff though, and the txv should work without it.

@ChrisJ It's definitely worth a try. I also just read your other thread about your thermostat issues. If you have an issue of pressurization or depressurization, the thermostat may be reacting to drafts from inside the wall, and potentially, from outdoor air. If I remember correctly, you are multistage with fan speed options based on indoor humidity? If so, the thermostat may be switching gears to fast for the A.C. system. It can take a TXV up to 15 minutes to stabilize.

Turn the system on high and use a laser thermometer or thermal camera to scan the wall surface across the thermostat location and a couple feet out each side. Also stick a thermometer probe through the hole in the wall where the thermostat wires exit. If you have temperature variations, you can be fairly certain that you have air ingress or egress. And the hole where the thermostat wires go through is not necessarily the culprit. In can come from other areas.

I recently had one of these jobs. Fickle critters for sure. What it ended up being was all the attic insulation above the stairwell had collapsed, leaving a large gaping hole with uninsulated walls and a return stud cavity with nothing but panning over it.

ChrisJ

Harvey Ramer said:

@ratio I imagine it wouldn't hurt if it doesn't get wet. That's some messy stuff though, and the txv should work without it.



@ChrisJ It's definitely worth a try. I also just read your other thread about your thermostat issues. If you have an issue of pressurization or depressurization, the thermostat may be reacting to drafts from inside the wall, and potentially, from outdoor air. If I remember correctly, you are multistage with fan speed options based on indoor humidity? If so, the thermostat may be switching gears to fast for the A.C. system. It can take a TXV up to 15 minutes to stabilize.



Turn the system on high and use a laser thermometer or thermal camera to scan the wall surface across the thermostat location and a couple feet out each side. Also stick a thermometer probe through the hole in the wall where the thermostat wires exit. If you have temperature variations, you can be fairly certain that you have air ingress or egress. And the hole where the thermostat wires go through is not necessarily the culprit. In can come from other areas.



I recently had one of these jobs. Fickle critters for sure. What it ended up being was all the attic insulation above the stairwell had collapsed, leaving a large gaping hole with uninsulated walls and a return stud cavity with nothing but panning over it.

Right now NJ Tommy wanted the dehu function disabled, so it's never actually been on. The system was running in low stage for quite a long time when I took the video showing the pressures.

The IR thermometer is a good idea though, I'll pull that out.
Right now I'm making up an insulated plate for behind the thermostat. I think attic heat is getting to the thermostat through the box it's mounted on.

EBEBRATT-Ed

So running low stage all the time is the fan speed constant? I know bulb locations change with different pipe sizes. I always thought 8 or 4 oclock was correct. moving it outside wont hurt.

Does it hunt on low stage and high stage?

Harvey Ramer

2:00 or 10:00 for 7/8" to 1-5-8". 4:00 or 8:00 for anything 2" and above.

ChrisJ

EBEBRATT-Ed said:

So running low stage all the time is the fan speed constant? I know bulb locations change with different pipe sizes. I always thought 8 or 4 oclock was correct. moving it outside wont hurt.

Does it hunt on low stage and high stage?

Yes, fan speed is constant, for each stage. Approx 800cfm in low, 1200 in high.

It hunts in both stages.

ChrisJ

Typical conditions on an 85F day. It's running non stop in low. High 80s and it starts going into high. Mid 90s and it's continuous in high.

Right now, it's 87F out with 55% RH. It's NASTY out.






What say you @Gordy ?

Gordy

Personally I find 72 degrees acceptable if the system can hold when worst case happens? Mid 90's high RH.

Personally I can be fine with 75 so long as RH is in check.

Set points of 72 in winter verses 72 in the summer are quite different. Especially if you dwell outdoors seasonally.

Question is with the txv issue getting ironed out if things change, or if it is really even a cooling performance issue verses an efficiency issue.

My only other thought is where set point settles in when cooking, or gatherings with many people take place.

Gordy

As for the size of your unit 3 tons for your square footage 1600 ish?

It's probably a good thing you went with a two stage. Other wise I think short cycle, and humidity control at lower ambients, and high humidity may have been a problem.

ChrisJ

@Gordy I suspect if anything, the smaller TXV will lower humidity more because the evap should stay at a lower pressure, more consistently.

That said, your responses kind of confuses me.
Earlier, you said 3 tons was oversized, and what I was aiming for was unreasonable.

Now, even though I showed you it has no problem keeping humidity low, and the system for me, is sized perfectly, now you're wondering what it'll do if there's a lot of people in the house or if someone is cooking?

So, now you've swayed the other way, maybe the system is undersized? I think you've gone nutty in the hay my friend.



As far as humidity, if my understanding of what @EBEBRATT-Ed said regarding how the TXV behaves. As the temperature in the house drops, so should the pressure the evaporator is running at, so it's dew point should drop as well. Meaning, the system should maintain reasonable RH indoors at 65F, 70F, 75F etc.

Oddly enough, best I can tell, Goodman's "Dehu" feature doesn't appear to work on this air handler though I will be looking into it more. From what I see, my static pressure remains the same and I don't hear any chance in the blower. I'd expect a 15% drop in blower speed to be noticeable. But, maybe I'm wrong.

ChrisJ

And this is why I never bother opening windows.
The temp will drop more, and chances are, it's going to be foggy.

Lovely.

Gordy

Sitting on the patio drinking hot coffee. You must be very delicate........

ChrisJ

Gordy said:

Sitting on the patio drinking hot coffee. You must be very delicate........

You're always saying we pay to be comfortable.

I pay to not sit in fog.

Gordy

My prior point was this. If you would not have went with two stage then at lower ambients maybe even design the system may have short cycled not giving enough run time to keep humidity under control. It's running flat out on 1st stage mid 80s. Disable 1st stage see what happens if unit is only running on second stage.



I'll admit I'm shocked that a 3 ton unit is running flat out at those OAT for 1600 SF. I'm not the only one that early on felt the same.

ChrisJ

> @Gordy said:
> My prior point was this. If you would not have went with two stage then at lower ambients maybe even design the system may have short cycled not giving enough run time to keep humidity under control. It's running flat out on 1st stage mid 80s. Disable 1st stage see what happens if unit is only running on second stage.
>
>
>
> I'll admit I'm shocked that a 3 ton unit is running flat out at those OAT for 1600 SF. I'm not the only one that early on felt the same.


Someone on the forum spent hours doing a heat gain and heat loss with me. When the heat loss matched what the EcoSteam calculates at zero degrees, I had a feeling we were real close.

This is a drafty 150+ year old house, it's not modern construction. Let's call "modern" being 1950s and up.

One thing did occur to me though.
This house may be drafty, but I know I always have plenty of fresh air.

Maybe that's a bad thing, but maybe not. Especially after someone has Taco Bell.

Gordy

You must not have much shading either. People don't realise how much shading can lower loads.

Gordy

Now track your kilowatt usage. See how much your using compared to window shakers.