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?