We are looking to installing Geo in our existing home in central Iowa and are looking for help. Our house is a walk out ranch with 1980/sq ft on main level and about 1200/sq ft finished in the basement. We currently are on LP which fuels the furnace, 2 - 40 gal water heaters for hot water and an other 40 gal water heater that heats the radiant heat in the basement. The two options we are looking at are as follows. 1) Forced air, 5 ton Climate Master two stage with a 6 ton loop field with a desuper heater. If we went this route we would do forced air up and down and not use the radiant heat. The reasoning for not using the radiant (on LP) is that the installer is afraid it would want to take over and the Geo and would not run as desired. *Issues: Would I regret not using the in floor heat? With only having one zone, will the basement be freezing in the winter? 2) Water to water, 5 ton Geo Comfort with a 6 ton loop field with a desuper heater. If we want this way we would have forced air up and radiant down. *Issue: Costs more and is less efficient(30% less efficient?) Questions: What option would you go with? Is the unit over sized? Is the 6 ton loop field over kill? What are your thought on a air to air exchanger? Humidifier? Are the quotes reasonable? The estimate is from a guy that I have heard many good thing about and has been installing Geo for over 15 years. From what I get from him is that he likes to over size the loop field often because the unit will be more effieciant. Thoughts? He thinks I should go with the water to water option because then I will have to zones--forced air up and radiant down. I will add the estimates in the morning when I can scan them in.
This should be entertaining? Hi and welcome. I will let some of the others address your units and configuration, I will take first bite at the loop field. If the house has a given load that matches the unit it should follow that the loop field should also match. Over looping is in-efficient to your wallet on install costs. We match the feet of pipe in the ground with a given load. In this case you have a five ton load and are going to add an additional ton of loop. How much additional pipe is that going to be, and what will it cost to install? Knowing the number will help you look at it from a math % standpoint. If your installer is known for this I would beg the question is it really helping the system or is it a insurance policy for the house load design? Not saying the firm is bad but I would want to know the answers to these questions prior to forking out more money for extra loop. The poster child for this is my own installation. I increased the loop by 50% for the upstairs and 30% downstairs. Had I payed myself that would have cost an additional 3,000.00. After 3 years of operation I only see minor advantages in ewt over our office mgr.'s house that we looped according to the design. hope this helps Eric
I agree with Eric. Find out how much the extra loop is going to cost. If it was me, I would want to keep the radiant in the basement for the comfort. But you have to decide if the comfort is worth the cost.
Eric, I was told that the additional ton of loop would be 900 ft at a cost of about $1500. Total pipe would be 6 X 900ft = 5400 ft. Not sure if this is correct but will check. Installers explained that the more loop you have the warmer the water will come in when heat is needed which in turn means more efficient and less run time. But I also understand its less efficient on the wallet. Thoughts??
If the installer can do 5 tons of load with 4500 feet of pipe in the ground, I would want to see the design math for spending an extra 1,500.00 to install an extra 900 feet? If the house load is five tons of loop, adding 20% more loop does not give you 20% more efficency. Everyone here agree's that if possible, spending monies on improving your homes insulation value's or reducing air infiltration will return more value for every dollar spent. If you have an extra 1,500.00 to work with I would rather you spend it on the envelope, not on extra loop. Eric
EWT This made me think a bit more closely. As we know, the loop is designed to supply water at a min and max water temperature (EWT). So really tonnage isn't a good way to describe a loop, but it is efficient for quoting purposes. But those EWT's are at the extreme ends of the heating/cooling seasons - or usually are based on the world matching designs. So how often is the loop at its min/max EWT? When I look at various WEL data for systems, it is not that often. A smaller loop "will get there more quickly and stay there longer" but efficiencies are such that this would translate in to very little operating cost (or savings for that matter) differences. Note - I'm not talking about a system being short-looped. I can certainly see +10% installation vs. design to make up for all those real-world issues and give a comfort factor. I can also see some arguing for an minimum EWT of 35 vs 32 vs 30 (my area type temperatures). But I can't necessarily see someone designing a system and then arbitrarily increasing it by 20% and assuming this will lead to any sort of savings. I believe this is where we see "diminishing returns" in money invested. A better sell for me would be them arguing the benefits of 35 vs. 32 EWT and installing a system based on that. But coming from someone who recently had conventional mechanical engineers arbitrarily request min 40EWT on a commercial system, I'm a bit sensitive about this. Want to kill a geothermal option? Put in some made up number like that and watch the loop suddenly multiple by 4x. I did kindly explain they best leave the design requirements up to me
To me this sounds like a good application for the synergy 3D or Hydron hybrid. As long as the existing radiant uses low water temp. Not sure what the installer means by "Afraid the radiant would take over". ChrisJ
The contractor that I used for vertical loops, gave me a bid for what the design load came out to be. After he got started drilling, it was going so well that he added an extra 100' to the (4) bore holes, to ensure there was not a need for strip heat. Even though he drilled deeper than planned, he did the drilling, put in the pipe and had them grouted in around (6) hours. They came back another day and ran the line into house and flushed and filled loop. I have a two stage 4-ton with desuperheater and am very pleased. I would plan on an extra water heater for storage if at all possible, so that you can maximize your savings. I would think that you could address the basement with zoning of your airflow. One thing is for sure, you will not get better advise than from some of the professionals on this site. I have learned a lot from them and hope that it gets more active in the coming months
It will be more expensive to go water to water, only you know if it is worth it. One thing you could do is keep the propane radiant floor as basement loads are fairly modest. It will have the added benefit of a emergency heat system easily run on a portable generator. There is no reason it could not work in concert with a water to air geo. 5 tons sounds like a lot for a less than 2,000 above ground sf house. 1 extra loop depending on electric cost, may save less than $30/yr. It will take a long time to pay for itself.
I am an Air Head, turned Wet Head There is nothing worse than a convert. Given what you have I would: Go water 2 water. Not many years ago I told folks here that even the guys inside the D.C. beltway would see the light on water 2 water. The water will supply the radiant floors well. You may need to change some piping. Look at a four pipe air handler. If not yet they will soon be equipped with ECM drive blowers. With your propane as a back up/aux heat option, a four pipe lets you run the heat pump 24/7 if needed. Then the propane can heat the second coil in the air handler when needed and only then and allow the geo unit to stay on line. I have three new projects here in Ohio, doing that. All three have radiant floors. Radiant delivery of heat is at least 30% better than air delivery of heat. Pin the loops to the load. Water 2 water piped and zoned correctly will allow the extra loop dollars to be spent on comfort and not on liability insurance. Water 2 water to a buffering tank system can allow a sub set of load priorities to be imposed that will give you the most comfort for the fewest dollars in both installation and operating costs. mho Mark ps. I have been doing geothermal since we ran out of natural gas when Jimmy Carter was President. I have been doing radiant not that long by about ten years.
Thanks for everyones replies!! So we have decided that vertical wells are required as there is just to much rock in our lot which adds about $4400 to the install. What we would be doing is 3 wells 300 ft deep with 1 inch pipe. Designer said this would be equivalent to 6 ton but is it? I guess my question is how do you figure how many tons that is? urthbuoy, stated that tonnage is not proper verbiage so is there a calc for this? Another reason he thinks a larger loop field is necessity is that the basement floor was not insulated like he would on a radiant floor. There is no insulation between the floor and the footings which leads to heat loss through the footings. It all makes since to me. What are your thoughts? Chris J A reply to why he thinks the radiant would take over. He thinks this would happen if we left the radiant on LP and Geo forced air up. It makes since because heat rises. He was telling me the water heater that is running the radiant now is way inefficient(like 60%) so it just does not make since to run it on LP because the radiant would try to heat the whole house and the Geo would not be used enough. Someone also mentioned that the basement could be reworked to zone it. We have thought about it and it would cost a few thousand dollars to do this so I would be better off just to go with the water to water. So after doing the number crunching it would cost us about $4500 more to do the water to water. If we had to zone the basement with the forced air it would cost maybe $2500 more to do water to water. We still have not decided because my wife is stuck on why would we spend more $$ on something that is less efficient?? How do I respond to that?? From experience, how less efficient is water to water vs forced air?? Thanks Jeremy
Pick a manufacturer and look at the tech data tables. Then do the math. Do not forget the delivery advantage of the radiant floors. I do not think the lack of perimeter insulation will matter much in the cost to operate the floor. If the floor was poured with expansion material around the edge that should be enough to nudge the heat into the space.
Mark, What do you mean by " Radiant delivery of heat is at least 30% better than air delivery of heat." Does that have to do with efficiency or comfort?
Jeremy, How much tonnage you get out of a given loop is determined by the local conditions underground. It is a function of the conductivity of the soils or rock. Every region of the country has an accepted rule of thumb for residential loops based on performance history of installed loops in the field. Where I operate we use 1.5 tons of load for a 300' x 1" loop, that means nothing for your area. Talk openly with the people you are dealing with about this and they should tell you what footage they are using in your area. Hope this helps Eric
D.C. around 12-25-2011 Eric: We can try again to meet. My best driller in Ohio, Yoder Geothermal is now doing 350' of 3/4" per ton, up from 300'. So things do change. We learn to go with the FLOW as it is, things change and we learn as we go. Yoder was a water well driller back in the late 60's when I met the company. They have well logs better than the ODNR. I trust their judgement. Jeremy: Yes. All of my radiant customers will never go back to scorched or warm air heating. There is the comfort. ASHRE had posted at their web site that radiant delivery of heat is 30% better than warmed air. Call me if you wish as I have several jobs going and am here tonight due to rain/sleet mix. Mark
There are a couple things why radiant is more efficient than air. The heat is where you would like to have it, namely right above the floor, whereas forced air is blow underneath the ceiling. Thus you a a perceived comfort at a lower actual temperature. In other words, usual with a 65 F radiant floor setting, your comfort is the same as with 70F forced air. Second, the energy to distribute the heat is significantly less with a small circulation pump for water than with a blower for air. Third, you can design a radiant system with an extremely low supply temperature, whereas the supply air temp of a forced air heat pump is relatively constant due to the constant return temperature. Reducing the supply temperature from 104F to 85F for example increases the efficiency of a 5 ton Hydron W-W by 29%, for life of the system.
