Radiant heat for lake house

[theoldwizard1]

I'm planning to build a lake house (of course, I still haven't bought the property) and am thinking about a concrete radiant floor. The concrete will likely have some type of decorative stain or other finish. I'm thinking radiant floor because the main room will be large and open to the second floor and I like the even warmth of radiant heat.

This house will not be occupied year round. In winter, I will probably set the thermostat at about 40F. I know that it will take hours for it to come up to temp if I want to use the house in winter (MI), but there will also be a wood stove.

Is a "sealed" system with propylene glycol (or ?) a reasonable solution so that the boiler can be turned off completely (temps can reach -20F) as an alternative to just leaving the boiler on low ?

My real concern is, in the summer, will the floor be "cold", especially on bare feet ? If the thermostat is set for 70F and the ambient is above 75F, the boiler isn't going to fire.

Can a radiant floor alternatively measure floor/water temp and turn on when it is too low ?

 

[koditten]

I have a radient system in my vacation home (Gaylord, Mi.) I need to leave the thermostat set at 50 degrees F. When I head up there in the winter, I call the neighbor and have him turn up the heat on Wednesday if I am going to be there by Friday evening.

I could not justify having this type of heat if I did keep it slightly heated all year. I love the floor heat, but it is not intended to be turned off completely. It just takes way too much energy to get the home heated to a comfortable temp.

Those concrete floors will take at least a day to heat up and another day to heat the house. If you are okey with shoes and socks for a day and using the wood stove you might do allright. Just make sure the thermostat is not being warmed by the wood stove. Your boiler will never come on.

If you are building new, you will most likely have the floor system engineered. the pro's will take in to account your desire to have warmer floors. the new systems are designed with a floor sensor to make sure that some heat is going into the concrete even when the air temp is not calling for the boiler to turn on.

The questions you are asking are not insurmountable. I am sure you have done enough research to figure out that this is a major machanical function of a home. You will need to have this system professionally designed. I love my floor heat systems, a person needs to know that they need to be carefully thought out by someone who is in the know.

Good luck

Kirk

 

[theoldwizard1]

Good info Kirk. I will spend a lot more time with heating contractors as I get closer to building.

What has been your own personal experience with the radiant flooring in summer ? Does it feel cold or damp ? Do you have floor sensors ?

What are your operating costs like during the months it is not occupied ?

 

[koditten]

T. Wiz:

I have 2 different systems. My detached garage at home with concrete floors of course is not noticed in the summer because I am always wearing boots in the shop. My system up north uses the pex between the floor joist system. The floor system in the cottage is hard to notice the warmth unless you stick your toes under an area rug. I only run the water temp at 115*. That heat has to move thru the subfloor, and tile/hardwood before it can heat the rooms.

The tile floor in the bathroom feels like a tile floor. The same with the hardwood floors everywere else. Not rally warm, not really cold, kind of hard to describe. My feet don't register that the floor is warm. What I notice the most is that my feet aren't cold.

I don't have floor sensors at the cottage. They really don't gain you anything when you don't have a huge heat sink as with concrete.

My bills for the gas to heat around 1100 square feet aren't to bad in my opinion. The gas bill for January was 115 bucks and February was 128 bucks. 20 dollars of that is just to be connected to gas. I have had cheaper bills even when I spent more time there. It depends on the amount of snow. The house is a chalet style. When the snow piles against the sides/roof I gain a lot of insulation. We didn't have a big amount of snow this winter in Gaylord. My bills were a bit higher.

To be honest, I don't know if I would like concrete thru my whole house. I work on concrete all day at work and look forward to the carpeting or wood floors at home(bad knees).

This is just my opinion. Please talk to the pro's. Dialing a concrete floor system up and down is not the way they work the best.

Thanks for listening

Kirk



Thanks

Kirk

 

[theoldwizard1]

Thanks for you information and opinion (on concrete floor).

I'm still researching a lot of things. The main reason I want concrete floor is low maintenance. I don't want carpeting. Area rugs are fine. I don't like vinyl. Ceramic or other tile is too expensive. Wood floors are expensive and are more easily damaged than concrete.

 

[94legaleagle]

I'm in North Dakota - So, my winters are colder than your winters

Anyway, I've got a lake cabin w/ a walk out basement and an upstairs - my lower level is heated by radiant floor heat, and my upper level is heated w/ a propane furnace (regular stairs b/w my floors, ie: my lower level is not otherwise open to my upper level) - radiant basement heat and upper propane heat EACH have their own thermostats

we use the cabin year round, although not as much in the winter - During the summer, I turn the radiant heat to it's lowest setting and the boiler does not heat at all

Then, about the beginning of October, I set the radiant floor heat to about 52 degrees - the upper level propane heater gets set to about 40 degrees

then in the middle of winter when I use the cabin I crank both heat settings up to 68 - 70 degrees - propane furnace upstairs heats upper level, no problem - In the basement where the radiant heat is at, I use an electric space heater to heat the air (during the winter when we use the cabin) - In about 12 - 24 hours, the radiant heat has caught up enough downstairs that I can turn the space heater off, or limit its use

you said you would have a wood stove for supplemental heat - that should be sufficient, in addition to your floor radiant heat (I'd like a wood stove @ the cabin in the basement, but layout is wrong and I'm not sure what I'd to chimney wise

hope this helps

 

[raspy]

Radiant floors don't necessarily take many hours to heat up and they are used during the summer because most folks don't like to step on a cold bathroom floor even in the summer.

I hear the tired old statement that they must be left on and it takes so many hours to heat up, etc. Not so if sized correctly and programmed correctly. In fact, I don't want them on all the time. Too much waste and not comfortable in most cases.

The easiest way to make the floor warm in a particular area, even if the room temp is warmer, is to use a setback thermostat.

Set the stat to call for 75 in the morning about an hour before you get up and then setback to 62 or so, when you get up. With a bit of experimenting you can get the timing just right. A nice warm floor just when you need it. This method uses the stat as a switch instead of a thermostat and will heat the bath floor even if the temp is warm. I only use floor sensing thermostats when I have a small radiant system inside a forced air house. Setback stats can be tuned to perform very well with radiant and I use them on all my systems.

Systems should be sized with about 25 BTUs or more per square foot for the whole house. This gives reasonable performance, and when heating only one small zone, like a bathroom, might deliver 100 BTU per sq. ft. or more.

Recovery in a proper sized system is not an issue, but it will never compete with a sudden hot wood fire of forced air, and come on in minutes. You can also install one of the new stats that can be accessed on line. This will allow you to turn on the system at the cabin before you leave home and be greeted by your warm floor when you arrive.

 

[nate379]

Have not been around one that didn't take at least a day or two to come up to full temp.

As far as cold floor well I never turn off my heat. Even in the middle of summers the lows are in the 50s so still need heat.

 

[Jackfre]

How big is the house going to be? Single story?

Yes, you can use glycol to prevent freeze-up. You have to maintain that glycol. It is not set and forget. It will also, due to viscosity of the glycol, require a bit more circ. Sounds like you will be having this professionally done so...hire the right guy.