Missouri System oversized....or something else?

Tamar one thing I should have been clear on is that the 30 kwh difference is running both units + the fireplace roughly 50% of the time for additional heat compared to running only 1 unit with no fireplace. I'm expecting to an even greater difference in usage when running the fireplace as well.

We were not charged when the contractor decided to upgrade the tonnage from 6-8. The bid price remained the same. In all reality, we actually made money on the increase. Our utility offered a $750 per ton rebate so the increase saved us $1,500. Our contractor was aware of the utility rebates and let us know that regardless, all rebates and tax incentives were ours independent of the bid.

One thing I would like to make clear is that up to now our contractor has been fantastic and responsive. We called last Monday about our concerns on energy usage and he was out the next day running tests. He checked flow rates, delta, made adjustments to the pump flow rates, return and supply temps, etc. He also took readings using a temperature probe because the units COP reading was low. He took the time to make calls and eventually got a call back from Modines engineer who took his readings and calculated the COP as 4.9. The other unit had a temp sensor out for the GWO. He will be back as soon as the sensor comes in to take a look at the airflow on unit I have concerns with. He determined at the unit everything was functioning properly and at the time I did not know we had an airflow issue. The duct work, install, was timely and professional. All solid duct, insulated, connected doped and taped. My reason for mentioning all of this is that I have no reason to think that our issues will not be taken care of, however I'm hoping to inform myself enough to ask the right questions when he does come back, especially about the oversize concern. I'm not concerned about what we paid or getting anything back, just want to get our setup running as economically as possible with the least cost or time to us or the contractor.

 

Hi Mark,

Thank you for your reply. As mentioned in the post above my main concern is making sure we are running as we should and receiving the savings we should expect for what was a fairly substantial investment. I want to make sure I'm asking the right questions of our contractor when they come back. I'll try to answer your questions below the best I can.

Why splits?
Our floor plans called for eventually finishing the basement and in the plans our mechanical room was located in the walkout garage. This led to a long duct run to one end of the house. This was the main reason for the splits. The contractor never asked if we would be willing to change the plans and move the mech room to the center of the house. Now that I know what I know I would have centrally located the mech room regardless of what it did to the basement layout. This would have also done away with one water heater instead of having two.

Big Glass scares HVAC folks to death because window manufacturers print numbers with tongue used to replace the thumb when typing numbers.
Big Glass scares HVAC folks to death because of the possibility of installation errors.
Agreed. This is one area that he did mention. I think we have a total of 34 windows in the house, very few are average size. Large glass doors as well.

In all the very professional pictures, I do not see duct work .
Main floor registers are in the floor so duct work is in the basement. Second floor registers are in the ceiling, so duct work is in what little attic space we have. Rafters are spray foamed so attic space is conditioned space. In the main living room area/loft there are also registers in the upper walls. Total of 4, one on each side of the loft and one on each side of the living room. These are tied into upper zones 4 and 5 to help with the main living area. Because heat obviously rises I have closed these in the heating season as they are not needed. You can see the upper wall vents in a few of the living room and loft pictures.

What machine serves which zones?
Unit I am running now located in the garage (walkout garage so still part of the basement) serves zones 2, 3, 5. The other unit that is turned off serves zones 1 and 4.

What are the ducting issues with the off machine?
I'm not sure if there are ducting issues or issues with the units blower not putting out the cfm's that it should. When I check the vents in zones 1 and 4, especially zone 4 there is very little air movement coming from the vents. While the garage unit is running the entire house right now with average run times of 20 minutes or less for a two degree rise, the unit in question is showing run times of about 1 hour for a 1 degree rise in temp.

With the troubling machine/system turned off and I would guess 3 zones, what is your comfort level?
With the trouble unit off, the other unit is running zones 2, 3, and 5. Our comfort level is good for zones 1, 2, 3, and 5 although the laundry room is a little cold. The ceiling fans move a lot of air and are doing a good job of moving heat around the main floor. Zone 4 is cool since the rooms are off of a hallway.

It seems to me you have a wallet, (electric bill) issue.
Correct. With all zones running the comfort level is perfect and just how we would want it. Even heat or air conditioning throughout. Very quiet system that you never notice.

You are equating run time with electrical usage, by emotion, not measurement.
Correct. I am basing this off the fact that our contractor did mention that he was concerned about short cycling and would look into it on the next visit. He mentioned that the units require a 10 minute run time to reach 95% efficiency. Our run times are often 12-20. If a short run time does not make a significant difference in electric usage then the short run times would not bother me. They do not affect our comfort level. My other concern is what an oversize unit and short run times does to our hot water production from the desuperheater. Free hot water is a very big part of the package benefits.

Thanks again Mark,
Jeremy

 

Mark I also think he had a hard time factoring in the spray foam and air movement. In our area nobody spends money on insulation. I don't know a single person, friend, family, neighbor who has spray foam in their house. Even new construction. It's all about making things pretty on the outside for the sale. I don't care what someone tells you about R factor. An R factor with batt insulation is not comparable to the same R factor with foam because of the difference in air movement.

After our home was sprayed, I foamed between any two pieces of framing that touched and didn't get covered in foam. If there was a double stud with a space that would hold foam I filled it. I did this for walls framing, window framing, etc. There wasn't a gap anywhere in the framing that didn't get filled. While there are a lot of windows, this should be a very tight house.

Jeremy

 

Jeremy:

The fog is lifting.

You have a very tight house, we can address that it may be too tight, as the winter goes on, and hopefully leads to spring.

We have two jobs in Northern Ohio that are spray foamed and the difference that system delivers is off the charts and out of the range of the heat loss programs I use. One is a rescue and one is a design build consultation. Both homes just blow the infiltration numbers out of the equation. To the point I am looking for new software that can account for either closed or open cell foam in the heat loss algorithms.

Lets go back to my quiz.

The reasoning for using splits is clearing up. So you have air handlers with geo coils? Where are the refrigeration units? Where are the air handlers? I have your drawings printed and on my wall here. It looks as if the house is split into two split systems, left and right. If you add a North arrow I will add it to my prints.

I am going to name your two units. The one that is running well enough to cover the entire comfort load will be the right unit, serving zones, 2,3, & 5. Do you have a better name? When I do this type of home I label or number everything. It makes communications easier.

I will name the other system, Bad Air Flow. My guess is that it is to do zone 6 when needed.

In a well designed forced air system ceiling fans should just be for show. I live in a home built in 1928 here in Cleveland, (GO BUCKS) with 10' ceilings. The duct work was designed for coal fired basement monsters. Those systems were gravity feed, as hot air rises. At some point the heating system has changed, but not the duct work. Now we have furnaces with blowers and a/c systems, so the ducting is not ideal for the current machines. I am not changing the duct work yet as we are on our first winter, but I am making changes to the air flow to get the most out of our comfort system. We are also like you tightening the envelope.

If you ask Tamar, she will vouch for me because, one day when I had more money than brains was going to drive from my home to hers to get her comfortable. Now I find out we may have talked on the help desk line for Honeywell. She knows if she had weakened I might still be camped in her driveway.

We need to move you from feeling, (based on run times) how your system works to measuring what is going on.

Big houses use lots of power.

Splits are easy to manipulate without equipment changes. I would like to see model numbers for the refrigeration and air handler sides of your home. Old "not for resale" pix of duct work would help very much.

warm regards,

Mark
OU '73 not OSU

 

Hi Mark,

I will try to answer your questions the best I can with my limited knowledge of HVAC. I also have an important discovery on our "bad" unit. Today I turned the unit back on and went into the settings on the orb controller and found that the unit has air flow percentages that can be set for each zone. When you open this option it resets to a default of even airflow split among the 3 zones, i.e. 33%, 33%, 34% for 3 zones so I'm not sure what they were at before opening. Before exiting I moved the airflow settings to 45% zone 4, 35% zone 1, 20% zone 6. 20% is the lowest setting it will allow. After making this change my airflow to zone 4 has increased dramatically so I am assuming the basement zone was set to a large percentage of the airflow.

One other item of note. With both units running, the "bad unit" or north unit was only reading a supply temperature of 87-88 degrees. The good unit or south unit is showing a supply temperature of 98-100 degrees. Now, on to your questions.

The reasoning for using splits is clearing up. So you have air handlers with geo coils? Where are the refrigeration units? Where are the air handlers?
We have two 4 ton Modine Water to Air Geo Units.
http://www.modinehvac.com/web/Geothermal/Products/WatertoAir.htm#.VLX0ICvF_PU
They are forced air heat/cooling units. The north unit and duct work is separate from the south unit and duct work. Both units share one QT 4 pump system and one loop field.

I have your drawings printed and on my wall here. It looks as if the house is split into two split systems, left and right. If you add a North arrow I will add it to my prints.
A new pdf is attached to this reply with north arrows for each level.

I am going to name your two units. The one that is running well enough to cover the entire comfort load will be the right unit, serving zones, 2,3, & 5. Do you have a better name? When I do this type of home I label or number everything. It makes communications easier.
The trouble unit is located on the north end of the house. Let's call it north unit. The unit I am using to run the entire house is on the south end of the house. Lets call it south unit.

I will name the other system, Bad Air Flow. My guess is that it is to do zone 6 when needed.
Yes - this unit would pick up the basement zone 6 if we were to ever need it.

I would like to see model numbers for the refrigeration and air handler sides of your home.
Units are Modine Geofinity. Model GFV048B2033RCX1ETL

Old "not for resale" pix of duct work would help very much.

Here are some pics of the basement duct work. This serves the main floor of the home.





D14_5179

D14_5176

D14_5174

D14_5173

D14_5171

I do not have any pictures of the attic duct work. Its currently closed off and I haven't cut an access to the north attic and south attic yet. Just figured I would do it if and when I needed access. I do know the same rectangular supply was ran to the attic space and then round duct branched off to the individual rooms. Round duct was the same size as the basement so I can get sizing if needed.

Jeremy

 

Jeremy:

We just might fix this by internet.

One has to love digital memory in jpgs. I shudder to thing how many terabyte of job photos I have. After working on some thing for so long one is sure they will be able to remember what is where., but as soon as the wall board goes up the memory is gone. Besides photo memory I also draw the control system. Six years out just because I thought it does not mean I will remember my thinking.

I need to hit it in the am but saw your post so I took a look before shutting down.

I will look up the units later. They look like conventional units not splits. The fan and the compressor are all in one box?

I will find out , but does ECM or variable speed blower ring a bell? Any idea if the units are two stage?

Here is what I see in your photos:

Variable speed, multiple stage, conventional up flow heat pumps, (I will look them up).

Some of the nicest duct work I have ever seen, not done with my hands.

Most of the near machine sheet metal is custom built by a pro.

Every seem is sealed with duct butter or aluminum tape. Either and both will out live me and you will get years of trouble free service from the duct work. Icing on the cake will be when you need to brake into the attic the duct work is wrapped not insulated on the inside.

Never mind he uses bubble foil insulation the guy is VERY good.

The zoning seems to be well thought out. We will learn if is was.

You spent a ton of money for this quality work and you are just a heart beat or two from having perfection.


What do we do next? I look up the machines, and you get me all that you can on the zoning, manufacturer, model and serial numbers, same for the tstats. You pay attention to how the home feels with the rebooted zone controller. You may have fixed the comfort issue yourself.

Once we have you and yours comfortable, we can start fine tuning the electric bill.

We may want to get you some toys. Cheap but accurate stuff so you can measure and learn what is really going on. We will tune the zoning system for max comfort, (that is why you bought the systems), and then dial down the heat pumps to run as little as possible. The heat pumps can be trained to stay in stage one as much as possible. It would be nice to have leaving air sensors control "Y" and "Y-2". When we are happy with the comfort we can start adjusting the air flow. The manufactures add the ECM blower drives for a reason.

I want the ceiling fans to be for looks. Since you and I can and will control the air flow I want you to know there are air diffusers that can shoot are like a hose nozzle shoots water.

I run with a dumb phone: 440.223.0840

I run with a smart wife, (owns the company) who uses a very smart phone with mobile hot spot and a very good tablet that dings when I get email: mark.a.custis@gmail.com.

This fix will not be as difficult as I thought it would be.

Warm regards,

Mark

 

I apologize for my lack of proper terminology. When I said split units I was referring to two units split to each side of the house. The term "split units" obviously refers to a certain type of system now that I see your questions. I also think I am slowly starting to figure things out. Here are a couple of notes before getting to your questions. The two tank hot water system shown in my pictures was new as of yesterday. I picked up a couple of Marathon hot water heaters yesterday to use as my powered tank. Prior to yesterday we only had a 1 tank system using the AO smith heaters that are now serving as my buffer tank. I mention this because we have been having trouble with not having as much hot water as we were used to the last couple of months. I checked the elements and they were good so we simply turned the heat settings up. My suspicion is that the desuperheater was actually cooling my hot water and causing the element to cycle on. This could be a big part of our increased energy usage. Now on to your questions.

I will look up the units later. They look like conventional units not splits. The fan and the compressor are all in one box?
Correct

I will find out , but does ECM or variable speed blower ring a bell? Any idea if the units are two stage?
Yes - ECM blower, two stage units.

Variable speed, multiple stage, conventional up flow heat pumps, (I will look them up).
Units are Modine Geofinity. Model GFV048B2033RCX1ETL Serial #:105120124713-1513. I can get the serial # off of the other unit if needed.

Some of the nicest duct work I have ever seen, not done with my hands.
Most of the near machine sheet metal is custom built by a pro.
Every seem is sealed with duct butter or aluminum tape. Either and both will out live me and you will get years of trouble free service from the duct work. Icing on the cake will be when you need to brake into the attic the duct work is wrapped not insulated on the inside.
Never mind he uses bubble foil insulation the guy is VERY good.
The zoning seems to be well thought out. We will learn if is was.
You spent a ton of money for this quality work and you are just a heart beat or two from having perfection.
Our cost for the system all in was $38,000 before rebates. After all utility and tax rebates our out of pocket expense was $20,600. To be honest with you I did not shop around. They had done work for a several other people I know and were also highly recommended by a good friend in the HVAC and metal fabrication industry. By your comments it sounds like the work is much better than average, which as I posted in my reply to Tamar I was very happy with the quality of workmanship and happy with the end result. Just trying to get a handle on if my electrical usage is normal or high.

What do we do next? I look up the machines, and you get me all that you can on the zoning, manufacturer, model and serial numbers, same for the tstats. You pay attention to how the home feels with the rebooted zone controller. You may have fixed the comfort issue yourself.

The t-stats are Hunter Model#44905. I leave them set at the same temperature 24/7. I have both units up and running now. I have the T-stats set to 72 for zones 2,3,5 running off of the south unit. I have t-stats now set to 70 for zones 1 and 4 running off of the north unit. My thought process on this is to continue to let the south unit pick up more of the load for longer cycle times. I have also moved the stage 1 span on the t-stats to a 3 degree change to hopefully slow down the cycle rate. If this is not necessary or doesn't help please let me know. Comfort level is good in all rooms now.

Once we have you and yours comfortable, we can start fine tuning the electric bill.
Now I'm getting excited. lol. Thanks Mark.

Jeremy

 

It seems you got a steal, for that amount of equipment and that quality of work. Just IMO.

 

Just read the IRS thread about duct work and exclusions. Looks like my out of pocket is going to be a little higher than I stated. Lots of good stuff on here.

 

Was there a heat loss/gain in any of the posts that I missed?

"Most the time you have to sort through the "experts" attitudes on this site. If they aren't being critical of you they are criticizing each other."

Ahhh a valuable contribution.......should help a lot.

 

No. I have not been able to get a copy from our contractor yet.

 

JK:

My feet are wet and cold, so until I thaw I may not get to your equipment.

If you are in comfort after fixing the south system zoning issue, relax. They will not turn off your power in this type of weather. Not even Mitt's.

Do not worry about the IRS and duct work yet. With or without geo you needed duct work. That is a battle to look at after we get your systems doing all that they can do.

Are you warm enough now?

Mark

 

Not too worried about the duct work. Our duct was free with geo unit and loop field purchase. And yes that was a joke in case I've got any black helicopters flying around.

House is warm. Thanks. The north unit seems to be more in line now with how the south unit is running. Good airflow to all vents and run times are not extended on this unit now. Now that both units are up and running I'm finding myself wishing for colder weather again so I can get an idea of run times after the changes. With the combination of warmer weather (39 degrees today) and increasing the t-stat differential to 3, the units barely seemed to run today. As of this afternoon my buffer tank water was at about 84 degrees. I did notice that turning on the desuperheater decreased my supply temps by about 8 degrees from around 98 to 90. Sound normal to anyone? Thanks Mark. Go warm up.

Jeremy

 

I'm suspicious that you are oversized and the zones compound the problem. Heat load would be first step and then manual D.

 

Does a blower door test help for an accurate heat load analysis? Our electric co-op will perform an energy audit for $100 that includes a blower door test.

 

AMI would you care to elaborate on what issues the zoning could cause, or a link to another discussion here that would be helpful? Just curious what effects it could be having. Also, the change to my t-stats seems to have made a big difference on run times. Even with warmer temps today of 48 degrees my run times on the south unit were in the 30-35 minute range instead of 12-18. My downtime has also been extended. In fact it was hard to catch one of the units running today to check run times. Also - the desuperheater seems to be working well. North unit at 89 degrees this evening and south unit at 105 degrees before we started showers.

 

Just a quick update on house performance since the changes. Run times are now much better. I am now getting 30-60 minute run times depending on how many zones call and when. Also much longer down times in between cycles. Hot water is great now. Since adding the buffer tank we now have plenty of hot water, more than before with a lower temp set point. Whole house energy usage is also greatly improved. Prior to the changes we were averaging 140 kwh's per day for the entire homes usage. We are now showing around 90 kwh's per day.

Also - in reading the units manual multiple times I have a better understanding of the zoning and how our system operates. The compressor operating speed and airflow is based on the zones calling for heating or cooling and the percentage of airflow entered by the installer during the commissioning process.

If <= 67% of total airflow is called, then 1st stage compressor operates low speed fan, 67% of full rated airflow delivered to zone(s) calling
If > 67% of total airflow is called then 2nd stage compressor operates high speed fan, 90% of full rated airflow delivered to zone(s) calling
The 67% and 90% numbers can be adjusted by the controller +- 5%.

Prior to my changes zones 1 and 4 were setup as 33% and 34%, thus they operated at 1st stage regardless if one zone or both zones were calling. By changing the two zones % they are now above 67% when both call and the unit is jumping to 2nd stage which has helped airflow tremendously when both zones are calling. In 1st stage we were not getting the needed airflow with both zones calling.

We are also going to go ahead and get a blower door test done to check ach. Our utility will also bring a thermal camera to help locate leaks. For $100 I felt it was worth it, if anything to see if we do have any areas that need to be tightened up. I was also able to get our homes volume for conditioned living space from our timber frame company. The total calculation including basement was 51,868 ft³. Basement is not currently heated so total if we exclude the basement is 40,465 ft³.

Edit: just checked meter and todays 24 hr usage midnight to midnight was 80 kwh.

 

Hi Mark,

I just caught the quote above in another thread. Was this in reference to me? If so what info would you like on the zoning and I'll be glad to get it. Would love to have your input.

Jeremy

 

A blower door and thermal imagery analysis for $100 is a steal, go for it! Your fellow ratepayers are subsidizing the cost since there is no way to deliver those services for just $100.

 

Curt that was my thought. They also will make recommendations for improvements and cover 50% of costs if you make the improvements up to $1,000.