Hello, I am investigating replacing our existing oil burner and central AC system with Geo. We have done research...but have found only more questions. I was wondering if this forum openly discusses technical issues concerning Geo with those not in the HVAC business. It has been my experience that the HVAC industry is very tight lipped making everything I do go through contractors. I need opinions and insights based on what is right for my situation without the pressure of a sale riding on it. Thank you for any help you can give.
Ask away But a word of caution...don't expect someone on here to necessarily hand over a full system design.
Ducting Ok...here it goes. We have a post and beam constructed house. Right now the heating is done with baseboard radiators which are low profile...easy to snake around the room in a shroud. Obviously, switching to Geo means changing everything over to air handling equipment. Is is possible to circulate the air via high velocity ductwork? The duct work is much smaller allowing us to use the same vias that the baseboard system does. There is enough room for a 4" duct in this space...but I think 4" is too small for a conventional system. -W
If I'm not mistaken, you can do radiant heat with Geothermal systems quite easily. I'm not an HVAC expert, though, but I believe they call it a water to water system.
baseboard radiators When I am told is the temperature difference with Geo is not great enough to drive a baseboard radiator system. The way it was explained to me is the radiators have to get pretty hot to encourage the air to move around and distribute the heat to the surroundings. Made sense to me. I have no idea how hot Geo can get the water....but the water leaving my boiler is something like 160F -W
Your understanding that geo is generally incompatible with hot water baseboards is correct. Geo heat pumps are compatible with high velocity duct systems such as Unico, but expect higher cost and some loss of system efficiency. Water to water geo can work well with lower temperature hydronic applications such as radiant.
A baseboard system is sized at 600 BTUH per liner foot at 180*, so if you looked up the out put at 120*F you may not have enough wall space to do the job. Google high velocity air conditioning, then look at the various design requirements. Most manufacturer's ducts will fit in a 3.5" wall.
I too felt like I was in a fog at first. Learning about Geo has been a steep learning curve. My understand is that radiant heat which uses hot water running through pipes under your floors does work well with geo, but it would depend on what your flooring is. Thick hardwood floors do not conduct heat as well as thinner sub-flooring under carpeting or tile. Keep asking around. Get more installers to come look at your house, try a few engineers too, their advice and proposals are usually free because they want to sell you their systems. You will learn a lot, about who knows their stuff and who doesn't too. I have certainly have been surprised. I am learning who to believe and trust - down to two firms from many, who is generally thought to provide the best service in my area (an important point) and who has experience in successfully setting up systems that function as they ought - crucial! (Check their references!) By doing so, I am getting much closer to deciding on the right set up and installer for my older home retrofit. Good luck with your search!
We have an oil heat system and just added the geo last december.I use the oil furnace blower,just added a new motor and belt.They replaced our AC A coil with the geo A coil.The fuel oil is set to come on if the geo runs for over 30 minuites,but even in -20 temps it hasn't came on.
I am cheap, but not free. I have never had a system not work. If it will not work, pay me for my time and I go home. I will not design or build it. Nor will I teach you to build it. Hey at 59 I get a little cranky. I started in geo in 1974.
The GT contractor I spoke to this morning was just telling me of a retrofit he did that was replacing a hydronic system using baseboard water. He said it works fine. I also did notice that Climatemaster sells a unit that heats the water up high enough for baseboard water. john
Drilling So I am hearing that Geo CAN work with baseboard radiators?? What is the typical temperature the water gets with Geo? If this is true, our entire approach to the problem would change. Routing ducting is THE biggest problem with this house. Windows span the entire distance between the beams...making it hard to hide ducts. The existing baseboard run just under the window...in a little enclosure that is about 6 inches high. We had a driller come out this morning. He wants to put the well about 35 feet from the house. Does this sound right? Wouldn't the water cool off by the time it got from the well back to the house? How close to the surface do the pipes lay when going back to the house? He claims for a 4 ton system we need two 300' deep holes. Does that sound right?
Generally you hear about bore-holes of 150'/ton. It's a "rule of thumb" which may not work in your case. It's best to let your heating contractor size your loops, not your driller, in general. 35' from the house shouldn't be a problem. The lines from the "well" to the house will be underground as well, so you don't have to worry about them "cooling off" while travelling that distance. Any amount of pipe in the ground below the frost line will "help." I am not an expert but I play one on the interwebs.
Goto Climatemaster's web site and look for the new unit they sell for water. I have two 300 ft holes that have not worked for my 4-ton system and we plan on drilling another 300 feet. It's a big cost to the project but knowing what I know now I'd ask for at least 20%-30% over what they say you need. GT is very different than gas/electric. Fill the tank and away you go with gas. The GT has no tank and there is a finite amount of heat you can safely remove from the ground. Exceed that and you end up in my shoes with a nice system but it just doesn't cut it on those colder days. I have really learned a lot and as some of the GT pros that opined on my thread said "eveyone buying into GT should read my thread before buying". I also think before anyone tells you two 300 ft holes are all you need ask them for a geologists report. If they don't have one than THEY DON"T KNOW! The thermal conductivity is so vital and just a little difference from in my case 1.3 to .8 means another 300 ft hole. In my case if the driller on the day he drilled the first hole gave his drill log to a geologist he may have realized that I would be having a problem and then contacted the installer and told the installer we need a third hole. The installer should have had a clause in his contract which would then put the cost back on me for the extra $3,000. It's not how it's done here and from what I see the rule of thumb is it and it's not perfect. It may work 50 or 70% of the time but then again how would anyone know if they were not like me. I just happen to be a licensed water operator in PA with just enough knowledge to realize I had a problem. Get it right the first time and you'll be very happy with GT. As for feet from the house 35 is fine. They will put the pipe deep enough in the ground that it's added loop length. The water from the ground is not warm and my house gets warm from entry water as low as 26 degrees from the ground. My loop is a closed loop and as the water circulates it cools the ground and the EWT gets colder to a point. My low point has been 26f. My static ground temperature is about 50f. Where you live will determine your static ground temperature and I would have provided it for you if I knew where you are. John
ClimateMaster's Water-to-Water Applications Manual has quite a bit of info on hot water baseboard in conjunction with geo heat pumps. Basically, with the right conditions, it is possible; but a direct retrofit to an existing fossil-fueled system is gonna be ...uh, "challenging." Looby
How to move the heat I think I jumped the gun. I need the geo system to both cool AND heat...so I am guessing the baseboard route is out. It seems to me I will have to go to some sort of forced air system if I want both cooling and heating. So then it comes down to using regular ducts or high velocity. I know at first glance it would seem "This guy is an idiot. Use regualar ducts and be done with it" In my defense, it really is a tough problem hiding conventional duct work. There are NO chases in this house to hide things in. If I create space to run ducts they will be in plain view. Running along the ceiling is difficult...as the ducts cannot cut through the beams...and all the works would have to go around them. This is possible on the first floor...as the beams are high enough to accomodate. But in the basement it is not practical...the beams are too low. So that means routing the duct around the walls (BTW...putting ducts inside the walls does not work either....as the posts supporting the beams block access) which IS possible...but a lot easier to do with the smaller diameter high velocity ducts. Does any of this make sense? -W
High velocity ducts are possible with geo--especially with EarthLinked DX. However, you may find for a 3 ton heat pump, you'd need a 5 ton Unico duct system. This would be quite a high price. From what I've seen, people tend to opt for trying to hide normal duct vs. spending the $$$$ for a Unico/Spacepak system. On Climatemaster's water heating unit getting up to the 145 deg. water mark is not very efficient. Actually, it doesn't matter what heat pump it is, if it's reaching that hot of water temps, the compressor is running at a fairly high head pressure. With most any water heating heat pump, the compressor could be manipulated to run that high of head pressure with an oversized water exchanger and theoretically reach that 145 deg. mark. The compressors, though, won't be lasting as long as they should. Another problem you'd find is that it is only reaching that 145 deg. temp at the end of its cycle. It's not a constant feed of that temp. I'd opt for a ducted system. Check out high velocity and regular. Where there's a will, there's a way. Good luck.
I have been told that Unico systems are loud ( blow air into rooms loudly) and are not effective. They were put into a large condo unit near me some years ago and I liked the appearance of them, but I hear from HVAC salesmen that people have been taking them out. I do like the idea of the smaller size of the ducts though, which would work well in my antique house. A few years ago, I contacted the person who Unico suggested for my area, only to be told by him that he doesn't like the system. I just contacted Unico again to ask for another name and also someone who is familiar with geo. From the speed of the returning email, I would guess a machine spit out an installer without regard to my request. I guess I will have to call Unico on Monday to try to get a live person.
using high V We've been using geo with high V air handlers no problem. They go very nicely together. We use water-water (Climatemaster) units with fancoils to the high V. Most of our work has been with Energy Saving Products Ltd., though they just had a fire at their warehouse here , they've got several distributors around.
