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Pondering radiant under floor whole house heat...

Posted by carpecattus (My Page) on
Wed, Jan 25, 12 at 17:57

Hello! Hubby and I purchased our dream property a year ago here in the Puget Sound area and hope to build in 3 to 5 years. We're taking advantage of this time to figure out exactly what we really need in our new home, and recently I've been researching heating options (including reading lots of posts here on the "Building a Home" forum and "Heating and Cooling" forum) - overwhelming to say the least! Our current home (1400 square feet, built in the mid 1980's) has a natural gas forced air furnace and our average monthly winter power bill (electric and gas combined) runs about $200, so I feel we are spoiled. Our property does not have access to natural gas so we will be dependent on electric and propane for our energy needs at our new home.

We are hoping to keep our new home to around 2000 square feet (one and a half stories with a large crawlspace preferred), and I am dreaming of a very quiet, comfortable heating system. I'm very sensitive to noise, especially low humming noise, and I find the sound of air rushing through our air ducts annoying. So many people seem to be such big fans of heat pumps (my Dad included!), but I'm really concerned about the noise factor. (My neighbor recently ended up removing a heat pump from her back yard, just two weeks after it was installed, due to the noise, even though the unit she bought was sold to her as being one of the quietest models on the market.)

Hubby and I installed electric radiant heat in our bathroom a few years ago and love it, but I'm well aware this would be too expensive to use for a whole house. I'm intrigued by Warmboard - I'm wondering if we go this route, and really go all out on insulating our home, could it be worth the extra expense up front? I've never been in a home with a boiler - are these noisy? We don't need AC - I know a lot of folks abandon radiant heat because they also need AC. While we will place a lot of windows on the south side of our home, the majority of the windows will be on the north side of our home to take advantage of a breath-taking view. We are also likely to install a high efficiency fireplace insert to take advantage of loads of wood we have on our property.

Thanks in advance for reading my lengthy post - any thoughts or experiences you can share will be greatly appreciated!


Follow-Up Postings:

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RE: Pondering radiant under floor whole house heat...

If you can afford the up front cost, ground-source heat pump might be your best bet if you will live there for decades. It would be a good match for radiant, in-floor. Can your fireplace be specified to heat water for your radiant?

I like conventional heat pumps. I like mini-splits even more. If there is a breeze when I am standing next to my outdoor units, I can't tell that they are running.

Consider hiring a local energy efficiency expert (resnet) to help you if your architect is not great in this area.


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RE: Pondering radiant under floor whole house heat...

Well you don't like noise, you don't like drafts and you don't need A/C.

But you do like radiant.

I would consider one of these in the link below.

Note, a Tulikivi is nothing like a conventional fireplace!

SR

Here is a link that might be useful: Tulikivi Soap Stone Heaters


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RE: Pondering radiant under floor whole house heat...

If you're still at the home design phase and you're considering radiant flooring, then I'd give serious thought to just beefing up the floor's load carrying capacity (add more floor joists) and pour a 1 1/2" thick layer of concrete of gypcrete within which the radiant tubes are embedded. Why focus on a compromise solution (warmboard) when the "better" solution (in terms of thermal mass, operating efficiency, warm zone dispersion, etc) is still available to you. For existing houses a concrete sublayer is usually out of the question because beefing up the floor to carry an additional 15 lbs/sf dead load is a huge undertaking, but for new constuction it's a walk in the park, the contractor simply reduces joist spacing and adds more joists and beams if necessary.

I agree with fsq4cw about the fireplace suggestion. If you a.) have a lot of wood and b.) want to heat with a fireplace, then you really should look up 1.) Masonry Heaters (Tulikivi is a brand that makes Masonry Heaters out of soapstone, which is known for having a very high heat retention capacity; and 2.) kachelofen, which are a variant of Masonry Heaters which are covered with tiles instead of bricks of stones, but work on the same principle, which is that their mass soaks up the heat from a daily roaring fire (95% efficiency versus much lower efficiencies from wood stoves and fireplaces) and then slowly releases that heat over the course of the next 24 hours. The added benefit is that the heating isn't boom and bust, meaning you don't get a huge temperature spike like you do with a metal stove and then have to refeed the stove as the temperature declines. Metal stoves don't have the mass to store the heat so they output the heat relatively rapidly and then cool down relatively rapidly.

Super bonus points for combining a Masonry heater with a radiant system which incorporates thermal mass in the floor. Give the house mass within which to store the heat and you're looking at a pretty low fuss system to heat the house which gives you silent comfort all day long.


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RE: Pondering radiant under floor whole house heat...

Thank you for the responses! Hubby and I are planning to make this our last home so we are hoping to live in our new home for 30+ years; we are willing to splurge within reason on better quality windows, insulation, etc., but we are building in an area where everything is more expensive. (We are figuring on spending $250 a square foot, and hope to do some of the interior work ourselves to stretch our dollars.)

We've ruled out mini splits because we don't like the look of the units on walls or ceilings. My understanding of air source heat pumps is that the decibel level is the equivalent of a vacuum cleaner - not horrible, but since we are moving to a very rural place precisely for the absolute silence we enjoy outside, I'm leery of going that route. (I'm thinking we need to visit a home show to see and hear some of these in person before completely ruling them out. My parents have an older model and it's horribly noisy.) It looks like a ground source heat pump has the same decibel range as a refrigerator, so perhaps that might be tolerable, under the house, but I'm concerned the combination of geothermal with Warmboard might give us sticker shock. (A recent blog I found written by a guy who built his $1,000,000 dream home in Seattle said he was quoted $5,000 per hole for a vertical loop geothermal system - he gave up on the idea when an energy expect told him he needed at least 6 holes. He also passed on radiant because he needed a/c as well; fortunately we don't need a/c, so I'm still investing radiant as an option for us.)

I really like the idea of the soap stone heater - I checked out the link and it looks like it could be a great option. (I grew up in a home with a wood stove and I love wood heat!) I didn't see anything on their website that mentioned the possibility of tying it to a radiant hydronic heating system - I wonder if that can be done. I also stumbled on something called a masonry fireplace - looks like a similar idea to the Tulikivi. I will definitely do some more research on the possibility of using a fireplace like this for hydronic radiant heating too.

Still curious if anyone has any experience with a traditional boiler and hydronic radiant floor heat and Warmboard. Wondering if a ground source heat pump and a boiler are similar in decibel levels.


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RE: Pondering radiant under floor whole house heat...

For more than one reason that you mention, I don't think that mini splits are for you, but I feel that I have to correct a misconception. The wall-hung units are most common, but you can install ceiling units that look pretty much just like a ceiling supply grate, and mini-ducted units in a hidden area that handle a room or two. They cost somewhat more.

If I did not need cooling, I wouldn't want forced-air of any kind either. OTOH, I have not been in a home with a modern, variable-speed system that has a return in every room. That would probably help considerably.

It seems to me that ground-source heat pump will provide hot water that is a good match for radiant, in-floor heat. Neither air- nor ground-source heat pumps need be noisy. As I said, I can barely hear my outdoor units running. I don't know what ground-source sounds like, however. If they are loud and the noise in the house is a problem, you could consider putting most of the equipment in an outbuilding. The drilling or trenching expense is really going to depend very much on your particular site so it would be good to investigate. You've got the time, right ;-)


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RE: Pondering radiant under floor whole house heat...

but I'm concerned the combination of geothermal with Warmboard might give us sticker shock.

How DIY are you and your husband? You can build your own GSHP from salvaged parts and drill your own wells. Here's a 100 page thread about how to do it.

I helped my friend put in Warmboard, so I have some familiarity with it. I'm not going that route for my house. Warmboard works by conducting heat through embedded aluminam spreaders, which means that you get a pronounced heat gradiant in your floor and your floor is cooler in the midpoint between the aluminum spreaders. Where Warmboard excels is that the performance it delivers is better than the less expensive alternatives, which are underfloor staple ups or a system without aluminum spreaders. If my friend could do his house over again he said he would have beefed up his floor joists and simply poured a thin cover of concrete and embedded the hydronic system within.

As for Masonry Fireplaces, those are what I was referring to. They can be built of bricks, stones, ceramic tiles and as with Tulikivi, soapstone, which is a premium product with the highest performance level (most heat retaining capability.) They can't, to the best of my knowledge, provide ALL of the hot water for a hydronic floor system, but they can supplement the heating requirements by having piping running into the Fireplace mass and then back to the water holding tank.

Here's an example of a Masonry Fireplace - 8,000 bricks, heats 3 floors of the home, has a built in pizza and bread oven, has a cooktop, and has a seating bench.


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RE: Pondering radiant under floor whole house heat...

Thanks for the additional ideas AlexHouse - you must have posted within moments of my follow-up post. I'm really liking the idea of a soapstone or masonry heater combined with radiant - quiet and toasty. I've read about the gypcrete option - we're hoping to do hardwood floors through out most of the house (and slate tile in entry, bathrooms and laundry room) and some of the sources I've read seem to indicate it can be a real challenge to install hardwood flooring over gypcrete, or if you lay a subfloor over the gypcrete and then install your hardwood flooring you're defeating the warming effect of the radiant heat. Or does having a subfloor and wood floor simply mean needing to run water at a higher temp - I wonder if this is something a masonry fireplace can easily handle, or could handle with just a little extra boost from a tankless water heater or boiler?

We will have to run the numbers and see which will work best for us. I'm thinking ground source heat pump could also be a good way to go (again, dependent on the noise factor), but we've been told by a guy who was working on an access road across our lot (it's nearly 7 acres) that the soil around our building envelope is some of the hardest clay soils he's encountered - like concrete. I've read that a clay soil can be more desirable for geothermal, but not so sure how trying to dig through this stuff to install tubing, vertical or horizontal, would affect the price.

As I mentioned, we are at least three to five years away from building (though I know that time will fly by!) - we are still in the gathering information and sketching home ideas phase. Hubby is an engineer so the more prepared we can be prior to construction the better it will be for us and the (yet to be decided) builder! :-)


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RE: Pondering radiant under floor whole house heat...

Geothermal is NOT a DIY project! It falls under the same category as what they say about those that represent themselves in court.

Even though I am a proponent of geothermal, it may not be for the OP due to the noise, unless you like the sound of a scroll compressor. Unlike an air-source HP, with geothermal you're introducing the compressor to the inside of the envelope. It's not overly noisy for most people but it may be in this case.

The OP should also know that clay is one of the least desirable soil conditions! It may still be possible to do a horizontal loop based on the size of the lot.

Geothermal however does remain the most cost effective (operating costs) active heating system available, particularly when coupled with in-floor radiant.

There is yet another possibility for radiant. Please see the link below. These are some of the most beautiful and avant-garde designs in radiant heating, not to mention efficient and perfectly matched to geothermal as well.

SR

Here is a link that might be useful: Jaga USA


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RE: Pondering radiant under floor whole house heat...

Why do you need a compressor in the house envelope to run ground-source hydronic heating systems? Is there any reason that all of the noisy stuff could not be in an outbuilding and the water piped into the home?


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RE: Pondering radiant under floor whole house heat...

Geothermal is NOT a DIY project!

Everything is a potential DIY project! A project's DIY feasibility is a function of knowledge and materials. Some projects require high levels of knowledge and some require high levels of manufacturing infrastructure in order to proceed, other projects have lower hurdles. Geothermal is definately within the scope of a a DIY project if people are willing to get up to speed on refrigeration theory. These DIY have dug their own vertical wells with their home built drilling units, they've welded their own pex with their home built units, they've made their own water/water heat exchangers, they've replaced refrigerants, they've tested and data logged their creations, they've repurposed equipment and, in the end, they have highly functional GSHP that match the COP performance of commerical models.

The point here is that these people have invested a lot of time on these projects, time to which they've assigned a dollar value of Zero (because they enjoyed the learning and building process).

You're coming off as someone who works in the industry and is trying to protect his own field from competition, say like a home designer flatly stating that home design is not a DIY project, or a home painter saying that painting a home is not a DIY project.

Geothermal DIY'ers face a knowledge hurdle - the materials needed are easy to get and build. The knowledge hurdle is higher than it is for painting and home design, or for that matter, plumbing and electrical, and if one wants to work with refrigerants in their DIY system they need a license in order to buy from suppliers, but getting the license isn't a huge multi-year studying effort, it can be done fairly quickly and then one needs some special equipment to handle the refrigerants, but when the alternative involves calling a specialist to install a GSHP and construct a well field, and the costs range from $20,000+, then for some people, the time and learning involved in a DIY project becomes worthwhile because they may be time-rich and cash poor and are willing to trade their time in learning and in fabricating in order to save significant cash.


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RE: Pondering radiant under floor whole house heat...

Re: ionzed

You could place the GSHP unit in an out building but it's not 'ideal'.

Re: AlexHouse

I'm not trying to protect the field from DIY competition. There are so few people that would attempt this on their own that it would be absurd to suggest that it would have any real impact. In fact it would probably be better for me if they did attempt this as I also consult on projects that are not working properly.

Look, you can research this for years, I suppose you can build your own drilling equipment etc. but from what I've seen on these DIY geo web sites of DIY pipe fusing I wouldn't want any of that in my front yard!

This is just one person's an opinion, if your pursuit of happiness involves building and installing your own home brew geo then knock yourself out!

You can also defend yourself from 'Murder - 1' but would you want to?

IMO

SR


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RE: Pondering radiant under floor whole house heat...

There are so few people that would attempt this on their own that it would be absurd to suggest that it would have any real impact.

This is a far different statement than "Geothermal is NOT a DIY project!" You're introducing new caveats, like "it would be absurd to suggest that it would have any real impact" and I'm not sure who was suggesting that such projects would "have any real impact."

The point is that the project is doable, efficiencies can match commerical units, the homeowner now knows all the ins and outs of his system and is, at the end of the process, knowledgeable enough to fine tune it and repair it when the time comes rather than calling in service techs to replace parts willy nilly.

The second point is that there is always a trade-off for saving money - the bigger the time/skill gap, as a rule of thumb, the bigger the savings. Here there is a big learning curve and welding, brazing, pipe fusion, working with refrigerants, etc and the result is a pretty big savings for getting up to speed on these techniques. Big time investment yields big money savings.


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RE: Pondering radiant under floor whole house heat...

Thanks again for all of your comments and ideas - the give and take of your posts provide us with great insights and ideas which will help us eventually choose the right system for our situation.

Hubby found the DYI attachment interesting, but as an overworked aerospace engineer he just doesn't have the heart to tackle a DYI project of this size. (Over 1000 hours of overtime last year, similar amounts for the previous five years, and no end in sight! We joke this is our dream house money.) We did a major remodel of our own master bath four years ago, which included installing electric radiant heat, and it took two years, partially due to hubby's lack of time and partially due to the fact his engineer training meant every thing had to be perfect! Slows everything way down! :-) (Our current plan is to have the shell of the home, plumbing, and wiring done for us, and then we'll tackle as much of the interior work as we can ourselves, over time.)

The JAGA site has some beautiful options (I love the scrolled radiator), but had my heart set on in-floor heat since this will be a small home with small rooms and would prefer to keep our wall space open.

Just out of curiosity why is clay soil considered not good for geothermal? (I can't remember where I had read clay soils were preferred over dry, sandy soils.) I want to make sure I'm fairly well informed if and when we start to talk to geothermal installers. We may rule that option out entirely if it appears to be a problematic option for our property.

Right now I'm really leaning towards the soapstone/masonry fireplace idea, and a combination of electric radiant in-floor heat (in tiled places where we might like heat year round, like the bathrooms) and hydronic radiant heat in rooms with wood flooring. Just need to figure out what will be the best way for us to heat and circulate that water. (If we use the fireplace to partially heat the water will we need a boiler or could a tankless or regular water heater handle the load?)


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RE: Pondering radiant under floor whole house heat...

Personally, I would look at the fireplace as a supplementary hot water heater, not the primary hot water heater.

For the masonry heater the more mass incorporated into the heater, the slower the ramp up and the slower the cooldown. This can mean one firing a day in order to achieve a steady state temperature. The higher the mass the more robust the fireplace foundation. One added bonus of a big fireplace foundation is the ash pit can be quite large, meaning that you can clean it out once a year or once very five years!

If I were in your shoes I'd decrease system complexity and do away with the electric radiant. If you're putting all the infrastructure in place to do hydronic, the marginal cost of extending it to another room is peanuts. Hot water heaters are not robust enough to be used as boilers and tankless is even worse.

Really, an adequately sized masonry heater is more than enough to do the job, similarly an adequately sized hydronic system is more than enough to do the job, so mixing the two where one of the two is the backup unit is going to create an overkill on the robustness of the backup unit. If you go for a small masonry heater as the backup unit then it's good for heat top off, to give that extra little oomph, but it would be undersized to heat the whole house, plus it would have quicker ramp up and cooldown cycles.


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RE: Pondering radiant under floor whole house heat...

Re: AlexHouse

I'm still saying it's not a DIY project. That doesn't mean that no DIYers can ever do it. For me it just means that most DIYers would best be advised NOT to do it. That's all.

It's just another opinion on the Internet. Everyone is free to disagree.

BTW: I don't know if that masonry heater you posted was a DIY project or not - but it is beautiful!


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RE: Pondering radiant under floor whole house heat...

I'm still saying it's not a DIY project. That doesn't mean that no DIYers can ever do it. For me it just means that most DIYers would best be advised NOT to do it. That's all.

It's just another opinion on the Internet. Everyone is free to disagree.

Well, other people have made businesses by disagreeing with you. A quick search reveals this company and I'm sure that there are many others just like them:

Providing Radiant Floor Heating Solutions & Plumbing Supplies to the Do-It-Yourselfer and Professional Installer


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RE: Pondering radiant under floor whole house heat...

Re: carpecattus

Neither clay nor dry sandy soils are ideal. Clay can slow the drilling process. Most drillers would prefer solid rock to clay. Clay has poor conductivity compared to most other overburden. Large amounts of expansion and contraction with change in water content are a characteristic of clay. This can result in voids around the ground heat exchanger HDPE pipes.

SR


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RE: Pondering radiant under floor whole house heat...

fsq4cw - Thanks for the soil explanation - that makes sense; I remember reading something about the challenges that clay soils can pose to foundations, due to repeated swelling and contraction.

AlexHouse - Thanks for the additional insight - another thing we need to consider is the fact we will be building in an area where we can expect power outages at least a couple of times during winter; a big plus for the soapstone/ masonry fireplace.


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RE: Pondering radiant under floor whole house heat...

Regarding power outages - the more thermal mass in your home the less oscillation there will be to your temperatures, meaning, if you have a power outage, the thermal mass will allow you to coast on your stored up heat.

The thermal mass can be built into the fireplace and/or it can be built into floors and walls. With a hydronic system, you can beef up your floor joist structure and pour a 1 1/2" concrete floor and your floor will have a steadier temperature state than a floor with warmboard or a floor with underjoist staple-ups.

As for the masonry heater, teh Tulikivi soapstone heaters mass (I believe) between 2 and 3 tons. The custom made masonry fireplaces, see picture in above post, can be designed any way that you like. In either case, these are not cheap options - the wood may be cheap or free, but getting the fireplace built is a big cost item, moreso than a traditional fireplace built onto a wall so that people can enjoy watching a roaring fire as the heat blast up and away through their chimney.

You're talking about two pretty big ticket items for a heating system - hydronic and masonry fireplace. A cheap woodstove would serve better for a backup heating unit when power is out. Again, you may not need one is your house is loaded with heat retaining mass.


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RE: Pondering radiant under floor whole house heat...

While appealing for some aspects, a massive heating stove is not a good thing if you have big temp swings outside, either diurnal or day to day. You could easily find yourself too warm in the daytime if your fire was high enough to keep you warm at night.

Even for your normal hot water needs, repeat after me, no tankless, no tankless..... it is an expensive way to heat water. Can you do solar with electric back-up in your location? If you do ground source heat pump, you can heat water with that.


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RE: Pondering radiant under floor whole house heat...

Thank you everyone for the continued follow up responses and advice. I'm spending every spare moment researching heat pumps, boilers, hydronic radiant heat, masonry fireplaces and even a bit of solar. (Although that might be a bit of a challenge for us - lots of trees along the south side of our building envelope, lots of typical Puget Sound overcast weather, and very cold winds sweeping down from Canada during the winter.) Last night I had a dream I was discussing all of this with my Dad - perhaps I'm spending a little too much time thinking about this! :-)


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