Just finished our retirement dreamhome in NE Idaho.  It's a big 5500 sqft. plus 2000 sqft. of heated garage space (huge ceilings).

Now that we are moved in, we have had nothing but trouble with our radiant floor heat and geothermal system.

The system appears to not be able to keep up with our heat demand.  We are in our 60s, so we like it warm (but not crazy hot).  We would like our house to be set at 72, but now that the system has been running for 3 weeks, it is still not able to get up past 68 even with the geothermal pump running full time.

We extract the water from the well and dump in a pond.  The heating guy says it should rise about 1 degree an hour, but we are flat lined at 66-68 degrees now, even though the thermostats are all set at 72.  All the floors are insulated with 2" foam or are poured with gypcrete.

Any suggestions?  I just spent $45,000 on this system.

Can you give us any more info and data? Are there any readouts or meters that give you:
1. The well water temperature extracted from the ground....50 degrees?? more, less?
2. The temp of the liquid in the radient floor pipes

Thanks so much for your reply.

1. Ground water temp is between 45-50 degrees.
2. From the storage tank, the temps get up to 110, but usually are around 100. And usually 90s once running through the house lines.

I'm not an expert in Geothermal and radiant floor heating (although I've played one on stage), but some initial browsing of the internet suggests that the water in the piping needs to be between 110 and 120. Assuming the water is flowing properly in the floors and not blocked by air/debris/etc. and assuming that the contractors poured the right amounts of mass for the floor and laid the pipes of correct diameter at the right depth, then the next solution to try would be to increase the temperature of the water in the floor piping.
The floor mass may take a day or two depending to reach the right temperature because of its mass.
The geothermal should still run efficiently at a higher temperature. You should be able to get closer to 120 degrees from that water. Is there any sort of adjustment to increase the water termp.
I mean, if everything else is right, the water temp must be the problem.

When you discussed the performance with the HVAC contractor what did he say? What is he doing to fix it?

Go to www.geoexchange.org and post there as well.

For $45K, the contractor should be camping in your mech. room until you're happy with the performance.

I agree with Greg and Arkie and while this reply contains no actual help I third the motion that the contractor should be hauled back to the house to investigate. My guy gave me a 2 year free service because he's only done a couple systems and wants to stand behind them. I saw some suspicious drips a few weeks after the install and emailed him. He came back the next day to investigate and repair if necessary.(Wasn't necessary, the lines going out to the ground get very cold and there is a ton of condensation on them...might have to wrap them in something). He's also constantly asking me if it's we're comfortable, warm, bothered by any noise, glitches,misprogramming of the zoning, etc. And I paid him only $24,000 in SE PA.

Not good, Not good at all. If the system can't keep up now, what happens when it really gets cold.  I really don't know much of anything about in floor radiant heat, but I'm curious, how many tons is the system? (whats the BTU output?).  Obviously the system is working, or you wouldn't be getting heat at all, but the concern is it's underrated for the size of the house. You did mention something about high ceilings in the garage, are there high ceiling through out the house? If so measure the heat near the ceiling, perhaps all you heat at the top of the rooms. In that case ceiling fans should help solve the problem.

Here's a question for people who have access to Heat/Loss programs, does the heat/loss program take into account the hieght of the rooms in the house? I would think that a house with the same square footage but with higher ceilings would require more BTU's to heat it.    

 

I'm certainly no expert on radiant heat. Try to find help from someone in your area with a thermal imaging camera. It should be helpful to see where the heat is, where it is going and why. Does one section of floor seem hotter then the rest? If so, can you put thermometers on various sections to actually measure the various areas? Be sure to cover the thermometers do drafts and air are not a big influence. Could it be that there are places in the house shell that "leak" hot air and cold air coming (drafts)? Also, if there is a floor covering over the concrete, what is it?

I would focus on measuring temps in various places of the system, including the slab.

Hope this helps,

John

Also, since it's a custom house, how was a heat/cooling load calculated? Did you ask several companies to "bid" on the system, and were all their specs similar? If not, can you share some of the other "recommended" systems? 90 degrees on the liquid in the floor just doesn't seem warm enough to me. I know radiant floor is a lot cooler than radiators (170 degrees +) but there's not a lot of heat in 90 degree water to cover that much house. I'd be curious of the temperatures both where it leaves the unit and heads to the floor coils and the return temperature. Also, if you shut down all the zones but one (maybe the smallest zone) does it get any warmer? That could help determine if there is enough heat for the house or not.

I know we're asking lots of questions, but the more information there is, the better.

Please let us know what happens. No matter what, your experience will help someone else, too.

Some questions...

Is your system triple function or just water-to-water?
If you have a desuperheater, how’s it performing?
How many tons is your HP system? How many HPs? How many GPM from that well?
Does your system have an ‘As Built Book’, detailing all the start-up procedures & measurements – including flushing & purging?
Does your system have a flow meter and EWT & LWT gauges?
You mentioned a ‘buffer tank’, how many gallons? Does it have EWT & LWT gauges? Is this tank a separate buffer tank from the desuperheater buffer tank?
Do you have a back-up for the GSHP; if not, why?
What can you tell us about the design of your radiant floor?
What can you tell us about your HP flow centre(s)?
Open loop? What can you tell us about the water quality of your well? Is there debris from flushing or mineral/biological material blocking your primary heat exchanger? How do you know?
How long/often does the HP run when there is no demand for heat?


That’s enough homework for now. You should have THE most efficient ACTIVE heating system - PERIOD! If you don’t have a (visual see-through) flow meter and EWT & LWT gauges, get them – you need them!

I can’t speak for all software with regards to height of ceilings, however, the Wrightsoft Universal software that I use does. This and MANY other factors are taken into account. All good calcs should! Regarding this case, the ‘huge ceilings’ of the garage are hardly a factor as the owner is using radiant in-floor heating. We’re heating from the ground up, as opposed to having to heat the entire volume of air mass, if we were using forced air. Above 6-feet who cares what happens? As long as your feet are warm; besides heat rises. This is the best way to heat a garage, especially with high ceilings, such as a municipal garage or fire station, where the doors may be opening & closing all the time. The heat stored in the slab offers the quickest recovery time & most comfortable heat; geothermal makes it the most efficient.

BTW: $45k would be VERY inexpensive (to say the least!) for a system like this in my area.

SR

More questions - Is the radiant floor a concrete slab? If so, was it installed on top of an insulating layer of foam? What type and how thick is the foam?

SR- Question for you. I don't have EWT, LWT or visual flow gauges. Can you make a recommendation for those?


John

The first questions are:
What is the BTU loss of the home?
What is the size of the heat pump?
What is the btu delivery capability of the radiant? at what temperature?
Who designed each component or entire system?
We can't help much without these answers.
Manual J loss calcs do include cubic feet (high ceilings) and anything over 6' in the air does add loss as heat migrates to areas with less heat.
If your contractor did the complete design and install of all components, then you should hold his feet to the fire. If you have different people who handled different phases then we need to ferret out the root problem before we trash anybody.
Main thing is to get this done ASAP as cold weather is coming.
Good Luck,
Joe

Check these links: http://www.blue-white.com/Products/VariableArea/F-400/acrylictube.asp http://www.flowcenterproducts.com/Accessories.htm SR

Thank You SR !

John

We can't help you if you don't answer our questions.
J