Texas POWER USAGE & PERFORMANCE? BOSCH SM060 - need input?

O.K
Looks like your ACH is a little high for a total SPF home. Not crazy but also not quite as tight as we design to. We design to 3 ACPD. Also I noticed in the photos of areas where the foam is pulled off of the wood joists. This is usually an indication of misapplied foam at the wrong spray temps and or mixture, or they were spraying onto a cold substrate. But believe it or not, it does have a dramatic total installed effect of the SPF hence the efficiency or performance factor drops.

 

Ok it seems as if we eliminated the envelope to a point.
I want photos of your duct system design, fittings, sizing,
Do me a favor the more info and photos of these I can get I bet I can help you figure this out the correct way.

 

The pictures in the report were problem areas identified by the auditor and the insulation company came back out to redo several areas and apply more foam. They came back 3 times and fixed the areas you see in the report. All connections are sealed and no leaks. What is ACH? I appreciate all of you guys helping me! Y'all are all awesome! I am in Chicago right now waiting on my plane to get here and I am flying thru Tuesday so I don't really have any more photos for you guys right now. Sorry about that!

 

I am out flying and will be home tomorrow night... This is a pic that my wife sent me - does this help you determine what I have?

 

ACH= Air changes per hour
This is the rate that your home exchanges the cubic volume air that is inside it. As we exchange that air we need to replace it which is usually unconditioned because it is made up from the weakness areas of your homes thermal envelope.
If this makes sense.
It tells us how tight your home actually is.
We know this because we are an HVAC mechanical contractor that also is an SPF only insulation contractor.
We are BPI certified.
We do this every day for a living.
Once you get back home send me as much design info on duct sizing, fittings on both the supply and return and photos
Thanks

 

Yes. Under "Ceiling Insulation" it says "R-19 Foam 2x6 Rafter ". That was the reason for my question.

 

thanks for the flow center pic.

Whenever I see 2 larger scale analog gauges for the loop delta T which go from -20 to 120 F, I do become suspicious. Why? Because they are not precision instruments, and they are usually off by a few degrees, and since we are looking for a delta T between 5-10 degrees, each degree off means your calculations are off by 10-20% (again for each degree off!), which also means that they are completely useless for what you need them for.

Then the second things I look for is the pump, or pumps, and whenever I see a 26-116 I know that the installer is not evolved. Why? The 116 makes about 10% more head pressure than the smaller 26-99, but uses 400 watts when running, instead of 230 watts for the 26-99. In other words it adds a large amount of electricity consumption without much pumping benefit. Now you have 2 of them, now take this times 2. So you are using 800 watts for pumping, when 230 or 400 watts total should do it.

The third red flag is the zoning. The key is to examine how the blower and the compressor is slowed down (which is difficult with a 2 stage heatpump) when only 1 or 2 zones are calling. It is concerning that the unit runs much in 2nd stage. Do you have a bypass damper?

 

I am seeing a 3 to 4 psi drop through the heat pump.

Why are the pumps different?

An energy audit using is like designing a control system with out being able to draw wiring diagrams.

IMHO.

 

Guys,

It appears I found a possible real issue in this system m. One of the pumps is very hot and pulling about 3.65 amps when the total should be 1.8 amps. The differential pressures are 24 and 35 and that can't be so or it would indicate a flow of over 30 gpm and we all know that is not correct! So, I am assuming restricted flows from a bad pump... Pressures and temps inside unit are off and Bosch has indicated that I have only been getting about 30 percent of my 5 ton unit's capacity and that I need to replace the pump... Input? Make sense to you guys?

 

While there might be something wrong with your circulator pump, I would question the accuracy of the gauges. Get a needle pressure gauge and measure the pressure drop with the same instrument, only then you get precise numbers. Just because you have lesser flow, whereas one 26-116 should actually be enough to keep the heatpump running happily. The suggestion by Bosch is right out silly, as long as the pump gets enough flow to not shut down, it will keep most of its capacity. If the flow for example drops from 16 down to 8 gpm, the total cooling capacity goes down by about 5%, not 70%.
I am not saying that their might not be something wrong with your refrigerant circuit, but a faulty circulation pump in a dual pump center does not cause a 70% drop in cooling performance.
Imprecise pressure and temp gauges like yours are not very useful since they lack the needed precision.

Again, do the basics, check the flow via pressure drop measurements, and check the temps, then you know if your heat pump works as it should.

I also again pose the question, do you have a bypass damper? You have 4 zones, and imagine if one zone calls, which one of them has to be smaller than 25%, how do you push 2/3 of the air and the heat into it? Unless you have some designed leakage into other zones. Recirculated air via a bypass damper will significantly change your refrigerant temps and pressures, and decrease your efficiency.

And again, (2) 26-116 using 800 watts for pumping when the heatpump is running is also very uneconomical.

 

Doc, sorry for leaving that out. I have a bypass damper - using Honeywell zoning has overridden the logic in the Bosch unit and we have found that zoning system's thermostats were running the system from the thermostats and stage 2 was being used almost all the time when stage 1 should be more than enough. We also used precise instruments to get readings and used a flow meter to test the loop fields and all is great! We have over 1500 of vertical loops at 1 inch in diameter. One issue that the engineer working the data is concerned about is that the entering water pressure vs the exiting water pressure is 11 to 12 psi different and calculates to more than 30 gallons per minute and with that and lamenter flows, we have too much water and they are concerned about too fast of a flow with high volumes not dumping heat back in the loop fields... Any ideas? We could not use the Bosch thermostat controls due to bad hardware and multiple failures. They had a production issue and the contractor good pissed, took the stuff off and used Honeywell thermostats and we just went in and took the Honeywell thermostats off of comfort mode and set the staging at 3.5 degrees for stage 2...

Pumps recommendations? All appears good - amps are below max rates of 1.8A

 

The bypass damper will recirculate the warm air back into the return intake of the heatpump, bringing up the refrigerant pressure. last time we run into a bypass damper with multiple zones, we measured an efficiency penalty of 34%, not to speak of the shortened compressor life. Combined with your 600 watts you waste with the pumps, explains your system inefficiencies you observe.

Too much flow does not reduce heat transfer to the loop field, you actually get a tiny bit more. But it might erode your heat exchanger over time, and cost a whole lot of pumping energy, especially with energy inefficient pumps.

How many circuits do you have in parallel. With 30 gpm, you don't have laminar flow, but turbulent flow. I really start to question wether the engineer actually is an engineer, and knows what he is doing.
Your whole system is designed and performs very inefficiently.

 

The contractor is solid! Great guys. They turned off one pump due to too much flow. We had a calculated 35 GPM of flow and not enough heat rejection in the field. We have 5 300 foot wells and the engineering indicates that it is right on. We had a 12 psi differential between entering psi and exiting psi. This was confirmed with precise instrumentation from Bosch. The flows were too high.
As it turns out, the well and loop contractor used water furnace data to calculate the flow pressure differentials instead of Bosch and the Bosch manuals call for less than 5 psi difference for a flow of 15 gpm .We had 12 psi difference for over 30 gpm - indicated in the water furnace manuals...




As to your remarks about the bypass damper, it is a Honeywell device. I was under the impression that the bypass damper opens when, for an example one ozone is on and the excess pressure is forced into the return air damper mixing with the inlet air, not as you described it above - mixing warm air into cool, raising the temps and pressures...? Please clarify your remarks - the way this thing is installed does not match what you are describing...

 

Do you have 300 ft wells, or 300 ft of pipe in each well, which would then be 150ft of bore each?

Yes, if only one zone is on (or 2?), the bypass damper opens and dumps warm air into the return, increasing the return temperature, which than will also continue to increase the supply temperature, which then gets dumped into the return again. The result is a much higher entering air temperature, which will increase the refrigerant pressure and make your heat pump operate very inefficient.

Your contractor might be a great guy, but whoever designed your system does not understand on how to make a geosystem operate efficient.

In addition, your numbers do not add up. (2) 26-116 pumps are not capable of pumping 30 gpm through the heat pump heat exchanger and the loop field. And again, it is incorrect that more flow reduces heat rejection into a loop field. Someone is telling you a lot of BS.
So where do you measure 12 PSI, and how?

 

Let's back up here.

First, I was talking about the bypass in a cooling mode not a hearing mode... So, in my scenario we would be dumping cooled air back into the return, right?

The wells are 1501 total depth. There are 5 wells at 300 plus 1 foot for the engineering.

The charts used by the well and loops contractor were from the water furnace manuals and at 12 ish to 15ish psi drop across the coaxial heat exchanger the charts were indicating a flow rate of over 30 gpm with 1 inch hdpe.

The Bosch charts indicate 3 gpms per ton at 5 tons and a drop of less than 5psi. All of these were measured at the unit using their or ports, not the gauges that I asked to be installed in the initial installation. These were put in at my requests.

We have double checked the loop fields with a flow meter and a flush cart to ensure that the 1" lines did not have any obstructions and that is where we got the 36 gpm flow rates with the valves not even being fully open...

We must use a bypass damper on a zones system in order to not override the one or two or even three out of four zones that could be calling. I am not real sure how they would have done this without this damper. Please expand...

Also, please expand on how it could be built more efficiently. We all want to know. Too much flow will indeed reduce heat deposits in the loop field... I do have a background in thermodynamics and hydraulics... Help me understand this...

 

Let's back up here.

First, I was talking about the bypass in a cooling mode not a hearing mode... So, in my scenario we would be dumping cooled air back into the return, right?

The wells are 1501 total depth. There are 5 wells at 300 plus 1 foot for the engineering.

The charts used by the well and loops contractor were from the water furnace manuals and at 12 ish to 15ish psi drop across the coaxial heat exchanger the charts were indicating a flow rate of over 30 gpm with 1 inch hdpe.

The Bosch charts indicate 3 gpms per ton at 5 tons and a drop of less than 5psi. All of these were measured at the unit using their or ports, not the gauges that I asked to be installed in the initial installation. These were put in at my requests.

We have double checked the loop fields with a flow meter and a flush cart to ensure that the 1" lines did not have any obstructions and that is where we got the 36 gpm flow rates with the valves not even being fully open...

We must use a bypass damper on a zones system in order to not override the one or two or even three out of four zones that could be calling. I am not real sure how they would have done this without this damper. Please expand...

Also, please expand on how it could be built more efficiently. We all want to know. Too much flow will indeed reduce heat deposits in the loop field... I do have a background in thermodynamics and hydraulics... Help me understand this...

 

Yes, when cooling. Forgive Doc, his experience is in a heating dominate climate and it is sometimes difficult for us to activate the reversing valve in our head. None the less, dumping cold air into the return while cooling will significantly reduce efficiency. You must measure the EAT (entering air temp) at the air coil to evaluate how much. It is hard to cool already cooled air. It is hard to heat already heated air. These actions make the HP have to work harder. A bypass damper has no place in an efficient system.

The max flow published in the Bosch charts should be considered a max recommended flow rate. Any flow rate greater increases the possibility of coax coil erosion. All indications show you are over pumping at the cost of efficiency and possible equipment damage. What was your pressure drop at the unit with one pump running (one disabled)?

A loopfield has a finite ability to transfer heat based on many varying conditions whether heating or cooling. As you reach your loopfields limit, pumping more is a wasted effort.

 

I would disconnect the "hot" pump, and re-measure.

 

Did you actually verify the HERS testing yourself. I have seen those test reports before when the equipment was not calibrated or is faulty methods of testing. Heck I have seen where companies have pencil whipped the reports.
So trust no one until you witness the testing and results for yourself at the time of testing.

 

Geoxne pretty much said it already. It does not matter wether heating or cooling mode, same concept. The efficiency of a heat pump in cooling mode also decreases by roughly 15% - 20% for every 10F of lower intake temperature. There are tactics by some zone controllers to slow down the blower when lesser zones are calling, and modern variable speed heat pumps can go down to 20% capacity to serve a single zone. 2 stage units like yours should not have more than 2 zones, since they cannot throttle back more than to stage one, which is usually 60-65% of total capacity already. They should have installed lesser zones, installed 2 smaller heat pumps instead of 1 large one if 4 zones were absolutely needed, or get you a variable speed heatpump.
Second, I don't know how you measured, but are you sure they measured psi and not ft/hd? Your loop field has a very low pressure drop, and together with your heat pump heat exchanger would need 80 ft/hd to pump 30 gpm, where as (2)26-116 in series can only do 20ft/hd at 30 gpm. That is without any header pipe from your heatpump to your loop field.
While increased flow can slightly increase heat transfer to the ground via more turbulent flow, more flow never reduces the heat transfer. Heat transfer is defined by the temperature difference between the 2 mediums (delta T), in this case the fluid and the ground (turbulent flow mixes the water better, thus slightly increases the delta T), and the conductivity of the material in between the mediums, and the surface area where that heat transfer can occur. A few other things matter too, but they are minor.
More flow will reduce the contact time of the fluid with the ground, thus in cooling mode will keep the delta T higher by maybe a few 10th of a degree, thus again more flow transfers a bit more heat into the loop field, not less.
You cannot change the surface area of the pipe in the ground, nor can you change the conductivity, so the only thing which changes heat transfer is an increase of temperature delta between the fluid in the pipe and the ground.

I outlines before, that you could get by with a single pump which uses 230 watts, instead you use more than 3 times as much pumping power every time the heat pump is running. The other culprit is your bypass damper. Both are no-nos in a modern and efficient geo system.

I outline this before, but you dismissed it. I am just trying to help you here, but you have been resistant to help. I think they tell you a lot of BS, and the pumping solution and the bypass damper tells me that your installer/designer is not evolved, so does the fact that those impossible flow numbers does not cause them to doubt them.
Instead you insist that you are getting flow numbers which are physically impossible, the numbers simply do not add up with the pumps you have. The only thing which adds up is the lack of efficiency of your system.
So put your background in thermodynamics to work and challenge your designers, they are the ones who should doubt their impossible readings.