We’ve covered the Loops and the Pumps/Flowcenter; however, the Heat Pump and Ventilation system still needs to be talked about along with a small revisit to the Pumps. This is a “system”, all of the parts have to be correct before it works well… including the ventilation.
My house is a 1 ½ story. I decided to concentrate on the second floor since this is the worst area in the house for climate control. An important rule of thumb is to ask yourself if all of the rooms “feel good”. If they do not “feel good”, then you have to ask yourself if the problem is ventilation or if your Heater/AC can handle the job.
My original ventilation system in the second floor consisted of two input vents (one in each room) and a hallway return duct. The air flow from the vents felt like a small hand held fan. Those rooms blazed in the summer and froze in the winter. Recently, we replaced the windows and added return vents to each room. This helped a bit. Input vents should generally be by windows, in our case they were in the center of the room. (I don’t know what the original installers were thinking.) The kids have complained each summer and every winter about their rooms since we moved in.
The ducts going up to the second floor started from the center of the basement and went directly to the center of the outside wall in the basement. They traveled along that wall to a corner. From the corner, they went up to the second story and then traveled along upstairs outside wall. From there, the installer took it from the wall to the center of the room. The ducts run about two million feet before they hit the register….
Without giving it a lot of thought, I felt very comfortable that the problem for these rooms was ventilation. However…. I should have put more thought into considering that if I increased the ability to put more air upstairs, that I could choke the downstairs creating another problem. If I stayed with the tonnage of my current system, I might have really been stuck. These do go hand in hand.
In this case, there was too little going into the room and nothing helping to remove air from the room. While we were increasing capacity into the room, I also put return ducts in them as well. Now, there is good air movement on the second floor.
Ventilation is important in a Geo system. Geos need air circulation…Why? I think most of it has to do with heating. My propane system generates very nice warm heat at the register. That furnace puts out a lot of concentrated heat that tends to dissipate throughout the room quickly. The problem with Geos is that they tend to produce “cooler” heat. This means that heat dispersion is not as great. The ventilation system now becomes very important part of the overall system in order to get proper dispersion. I need to get that heat in the farther reaches of the room without relying on “hot” heat dispersion. This means my ventilation system needs to provide good air movement.
If you have hot spots or cold spots in your house, I would strongly recommend talking to a ventilation specialist and paying them for their advice. They will know if you need changes and can help create a solution for you if you move to a GSHP. GSHP’s do in fact move a lot of air, you need to be ready for it.
Some folks feel that a great ventilation system with a poor GSHP is much better than a great GSHP with a poor ventilation system. This is something to carefully consider. Looking back, I tend to agree with that statement. If your ventilation is poor, you are going to have to run the system harder, pay higher bills, and reduce its overall lifespan.
Another issue with the ventilation system and the GSHP is that homes vary widely with regards to insulation, orientation to the sun, exposed surface area, windows, wind, height, etc… Ventilation requires a lot more planning and thought work to do a good job… Again, think of the ventilation system and GSHP as one big “unit”.
In my house it “looked” like most of my ventilation system was pretty good and that all I needed to do was get more air flow upstairs. Wrong! When I was talking to a Heat Pump vendor about installing the Geo system, he pointed out that my main ducts were fiberglass… and old at that. He suggested that I get rid of them. Overtime, this stuff starts breaking down and can circulate this stuff as it breaks off. He also noted that the overall size of my ducts did not match the volume of air that a 4 ton GSHP could generate. So, the main ducts had to go as well.
From what I understand, each ton of cooling requires 400 Cubic Feet per Minute (CFM) of air flow to properly ventilate the house. I have a 4 ton system. Thus, I will get 1,600 CFM out of the GSHP. My main ducts were undersized to handle that volume of air. Thus, I had to get the main ducts upgraded. Note: These numbers are “averages” and “generalizations”, your mileage may vary and I would encourage you to do your homework in this area.
With regards to the upstairs, there was really no easy way to get more air upstairs. There also seemed to be an issue with how the exhaust flue was right next to return duct in the basement going up to the second floor. If the exhaust flue was leaking into the return ductwork, there was definitely a safety problem.
Right off the bat, my ventilation contractor and I knew that I needed more air upstairs and that the furnace was going away. This left the Hot Water heater as the only other system needing the flue. It dawned on us if we replaced the Hot Water heater with an electric one that we could get rid if the safety problem AND reuse the flue space to put more air upstairs.
Since we had an open space to get more air upstairs, it was really cheap to fix this issue… in fact it was only $850 to upgrade the ventilation system. Unfortunately, it also made me get a new Hot Water heater and find someone to install it. (Another thing I had to do.) After reading some promotional material for Geothermal systems from our local electrical Co-Op, they stated that they would provide a free Hot Water heater for Geo installs… for new construction. I went ahead and asked them for a “break” on this. My reasoning was that existing homes are more expensive to retrofit with Geo than new construction… therefore, folks like me need more incentives. I picked up my new (and free) Hot Water heater a few days later… It cost $100 in order to get the lifetime warranty and bigger unit. Two days later, a friend of mine who has a really flexible schedule and is in construction, offered to help me put it in. This portion of it worked out really nice. (Two months later the Co-Op discontinued the program and now they cost $650.)
When converting from gas/propane to electric there are things to worry about. You have to get the electricity to the water heater. This can be challenging depending your circumstance. Also, with my setup, the copper pipes did not line up like the old one did. We had to do a lot more soldering than both of us wanted.
After the hot water heater went in, I called the Ventilation contractor to install the new duct work.
The only thing I did special with the How Water Heater (HWH) was to put in two more T’s and three more valves. Without getting into a big description, since I was already soldering, I decided to try to make it VERY easy for the GSHP desuperheater (desuperheaters are covered later) to be hooked up to the Hot Water heater. It’s kind of a funky looking setup; but, it has to be able to work with the current system and the new system with minimal re-work. Eventually, there was a problem with this setup.
The catch is that your Hot Water Heater has to be large enough (talk to your GSHP manufacturer) to handle the desuperheater. I had NO clue about this and frankly got lucky. Also, some government incentives require you to have a desuperheater.
Now that the flue issue is cleaned up and the ventilation system was going in, I decided to settle on a simple manual damper to control air flow upstairs. The lever allows you direct more or less air upstairs. Since heat rises in the winter, you want less air to go upstairs. In the summer you want more. I will have to adjust it twice a year. Also, I wasn’t ready to afford some of the automated stuff… I guess I’m forced to doing a 60 second lever adjustment in the basement twice a year.