Radiant or Geothermal Heat?

[Paddy]

Where I'm to build, I have ele or get a propane tank. The concept of Geo-thermal sounds good. That is you pay to move the free heat of the ground.

Radiant has some up sides too. I also plan to build with concrete and it goes with floor heating quite well. Down side is you still need dust work for your AC. I have heard saves energy costs because it feels warmer coming from the floor. As an enginerd, Btu is a Btu so I can't quite get the cost savings issue.

So...what's your thoughts?

Patrick

Both have alot of up front costs.

 

[inveresk]

I've lived in a number of radiant floor houses and as an architect it's usually my first recommendation to clients for a heating system here. When I remodel my current house, radiant heat will be the heating system of choice.

Benefits are:

1 Entirely even heat distribution throughout the room. There are no heat bulges such as you get with baseboard heaters or with warm air. This is much more comfortable and better simulates what it's like living in a warm climate.

2 You don't pay to heat the ceiling. With conventional heating, the temperature at high level is higher than at floor level. Not so with underfloor heating. In fact the temperature at head height is slightly less than at floor level. This makes for an efficient heating system.

3 If you use a condensing boiler, you can get close on 95% efficiency. (check out the Viessmann web site - www.viessmann.com). Condensing boilers work better at lower temperatures, when they're in condensing mode. Flow temperature for underfloor heating is around 50oC which is perfect for a condensing boiler. Conventional boilers usually output hot water about 80oC.

4 High thermal mass. Because radiant heat effectively uses the whole floor plate as a radiator, the thermal mass of the heating system and the house is higher than with timber floors which helps to flatten out temperature bulges, in turn providing for more even internal temperatures.

 

[Mavrik02]

I researched both for our house. I wanted to do radiant throughout the whole house simply because of the uniform heating, lack of on/off blowing air and because it doesn't take the moisture out of the air. However three different contractors told me that my house design would require "suplemental" heating for those really cold winter days. I thought I couldn't afford to put in two types of systems but as I look back at it I may have done things differently.

Geothermal was a nice alternative to forced air gas but too expensive to implement in my house.

In the end I went with radiant in the basement (about 2100 sq ft), forced air gas for the main living level (2100 sq ft), forced air electric for the second floor (900 sq ft) and a Quadra-Fire fireplace (designed to heat up to 3500 sq ft). Yeah, even after all of that the geothermal was still 2x the price.

I love the radiant in the basement! The forced air electric up on the second floor NEVER runs (mostly for AC in the summer just like the contractor said). The firplace runs everyday and heats the whole house except the three bedrooms on the first floor. Since it is designed like a wood stove we can even run it at night unattended. The main forced air gas furnace runs mostly only at night or when the wife lets the firplace burn out.

If I had to do it all over again I would put radiant heating everywhere possible. The geothermal is nice if you can afford it because it gets you out of the heating oil/gas price fluctuations but it does consume electricity.

They are very different methods to bring heat to your house. What might be "best" for you will really depend on your house location, type of home design, local gas/oil costs, type of flooring you want to have, initial install costs, etc.

Good luck.

 

[bird1968]

You can have both....

There is some geothermo heatpump, that have a multi-task.

There a in-ground loop required & duckwork for your A/C, but this unit also have one or two extra water cuircuit.

These can be pipe into the cement slab, pipe into your swimming pool & a hot water tank.

The idea is in the summer you got A/C in house & it heats the pool.
In the winter it heats the slab.
It can Pre-heat the domestic hot water.
It's a bit more expensive, but a cheaper solution if your looking for all of the above.

 

[Paddy]

I do like the sound of the even heat though with a concret house, I hope to get that via thermal mass. One of my concerns is AC. It's very hot and steamy here in S. Indiana.
With radaint heat you still need a conplete duct system.

What do you reccomend to your clients for AC? Duel system?

If I had gas, radiant heat would win but delivered gas and ele are expensive.

I will have about 3500 sq ft.

Patrick

 

[inveresk]

I posted a reply earlier but can't see it in the thread so here it is again . .

Patrick, for three years I dated a beautiful girl from Louisvlle and spent a lot of time there so know how hot and steamy your summers are. If I lived anywhere in the southern states, I'd be sorely tempted to use Enertia Building Systems' designs - www.enertia.com. The company is run by a guy called Mike Sykes. Mike devised an ingenious and award winning passive solar heating and cooling system. He's an architect with a degree in mechanical engineering. I've inspected Enertia's houses in 3 southern states (he's based in NC) and I can attest to the fact that they work well and his buildings look great.

Using Enertia's passive solar system with solar panels and a heat pump operating underfloor heating would be my choice and the same heat pump and u/f piping could give you supplemental summer cooling if you needed it.

George

 

[Paddy]

He has a nice web site. Indiana does not fair well on the solar heating scale. I.E. Indiana cold days are cloudy. We do have some daily temp flex though and good for Thermal mass. That is one reason I will go concrete. I travel to Italy quite often and like the designs in concete/stone.

I have friends with Geo and friends Radiant, both say it's the best! You know how it goes, "I made a good choice..it's great!"

Patrick

 

[inveresk]

Same principles of sound solar design apply regardless of what the construction material is:

1 Locate main living spaces on south side of building.
2 Place garages, stores, utility rooms, circulation spaces on colder north side of building where they can act as thermal buffers. This also helps with 4 below.
3 Maximise southerly glazing.
4 Minimise northerly glazing.
5 Build in high thermal mass.
6 Insulate highly.
7 Try to maximise internal volume/surface area proportion. This also helps with resource efficiency (more bang for your buck).
8 Use renewable energy if possible.

 

[robison]

2 years ago we built a home in Western MA with radiant heat. After living here through 2 winters I would not look at anything else.

The colder it gets outside the warmer the floors get. Since the bed sits on the floor - it's warm too. On a 10 below night you don't even need a blanket!

There are no cold surfaces inside the house - tub, toilet, floors . . all are warm. It's very nice.

Radiant is considerably more efficient that forced air. It's a lot more comfortable. There is no temperature gradient from top to bottom. If you climb a ladder to the ceiling you'll find the air up there is cooler rather than warmer as in most heating systems.

We find the house stays cleaner because there are no air ducts sucking air from the floor and blowing it around. There are no air currents like you find with baseboard heat either.

In our system we embedded PEX pipe in the slab for the first floor and stapled PEX to the subfloor with aluminum reflectors for the second floor.

I have numerous photos of the installation if you'd like to see anything.

You might look ar Radiantec of Vermont for design info. And I recommend the Weil-McLain modulating boiler for a large home.

 

[dooleysm]

We put in a geothermal system when we built last year near Jasper. I couldn't be happier. We kept our thermostat at 72 last winter and our highest electric bill was right at $100. We have all electric, minus the gas stove/range.

I've heard good things about radiant as well, but our builders (my father-in-law, my wife, and myself) didn't have much experience with it. I like the idea of not drying out the air, because we have to use a humidifier in our room at night because it gets so dry. I do wonder though, how well it works to have radiant heat in the basement. We spend very little time in our basement now. It's mostly storage. I'm sure we'll use it in the future as our family grows.

Guys with radiant heat, how does your usage of your basement space affect the decision to go that route?

 

[Paddy]

Both systems sound good. What size is your home?

Patrick

 

[keeney]

I have a finished portion of the basement with radiant heat, and it would not be nearly as comfortable without it.

One portion is a guest bedroom and bath. With the radiant heat, the floor stays nice and warm, and you don't even feel like you are in a basement at all.

The other area is a family room with home theater. When you take your shoes off, or if the kids lay on the carpeted floor, its a lot more comfortable. Without the radiant heat, these rooms would be a lot less comfortable places to use.

The other portion of the basement is a workshop. There the radiant heat is nice because it doesn't circulate any air to/from that area. Fumes and dust generated in the workshop are not circulated into the remainder of the house.

Each of the areas is on its own zone. I generally keep the shop set down around 55 degrees unless I am going to be doing some painting or something that needs higher temps or if I know I am going to be working in there the whole weekend or something.

The guest bedroom is kept around 60 degrees when unoccupied. There was that one time when my mother-in-law came to visit and we forgot to turn the heat back up again, though... I swear, it wasn't on purpose!

- Rick

 

[dooleysm]

My house is around 2300 square feet on the first and second floors. The bulk of the square footage is on the first floor. The upstairs only has 2 bedrooms and a good sized full bath. The basement is the same size as the first floor. We have ducts down there and plan to finish it at some point, but as of now, it's just storage, and we don't have the ducts open.

My brother-in-law, the architect for the family construction company, generally tells folks that with a 2500 square foot house, a geothermal system will pay for itself in 8-10 years.

Additionally, they are a regional supplier for and build most of their homes with RewardWall ICF's (Insulating Concrete Forms). We used these in our basement and were very pleased. They are lego-looking blocks of styrofoam that you set on a footer. You stack them up, cut windows and doors in, lay rebar in them, and then pour your basement into them. They stay up and add a very significant amount of insulation, both inside and out.

They've done whole houses in them. You can't tell a difference when the house is finished. They claim you can heat your house with a match. In fact, in one house they built the family bought a ventless LP fireplace for the basement. They returned it because they couldn't run it. It got too hot in the house.

 

[flwiii]

Would the opposite be true? Could I cool the house with an ice cube?

 

[thcri]

Out of town a lot lately so I am way behind on TBN. Anyway we do a bit of Geo-thermal and the last house we did we used a water to water heat pump. Along with a storage tank and domestic water heater this system did all of the wirsbo in the winter by heating the water in the storage tank and then the storage tank heated the pipes in the floor. This system also heated the domestic water with electric heat coils for back up. Then in the summer we chill the water so we can send the water to an air handler with a water coil in it. This coil can also be used for heat if we wish. This system works great and the customer has the comfort of the wirsbo heat.

We are also doing a house right now that has 5 water to water heater pumps in it. The loop for this system is a 25 ton loop. Again wirsbo throughout the house for heat and air and ten air handlers for air distribution in the summer time with chilled water coils.

Works great.


murph

 

[Paddy]

This sounds interesting. Geothermal with radiant. I like the idea of paying to pump free heet to....the floor!

Best of both worlds.

Patrick

 

[dooleysm]

Perhaps, but you'd be standing in a puddle of water once all the humidity condensed.

 

[Paddy]

Yes, that's why I stated pump free heat to the floor. AC wound need it own system.

It is best to have your heat come from floor level and AC from the ceiling.

Patrick

 

[Paddy]

Can anyone provide a basic cost break down for the Geo-Thermal. That is field loop or wells, unit.

Patrick

 

[Piedmont3]

We built a new home last year. approx 2700 sq ft. 3 bedroom, 2.5 bath. We have a geothermal heat and air unit.

Our Pipes/loops are in 6 each 4" diameter wells that are 115 feet deep.
Our heating and air conditioning bill has been wonderful in our new house. We also spent good money on very good windows, and additional insulation. Our house is total electric. including water well pump. Our largest electric bill so far has been $128 and change.

Here is the kind of unit we bought.
Water Furnace
The difference in the up front cost is quite substantial.
The Local Heat and Air Contractor qouted us $12,800.00 for the highest efficiency electric heat pump and central air conditioning system they sold.
The Geothermal unit cost us $20,500.00. The man that installed the system is someone I have known and done business with for about 15 years. /forums/images/graemlins/smile.gif
It didn't seem to help with the cost. /forums/images/graemlins/confused.gif
The man that dug the wells for the loops used the same kind of truck/machine that the water well driller used.
I am sorry I don't have the cost of the individual pieces.
Hope this helps.
Jeff