Introduction and first question (hydronic floors)

shelton

Hi all,

My name is Chris Shelton and I live on Camano Island, Washington, roughly an hour north of Seattle. For the past decade we’ve heated with wood exclusively. It’s nice and romantic and all but it’s also kind of a pain in the ****. We want a more conventional heat source. My wife wants heated floors. So by extension guess I want heated floors too.

But I have one big thing going against me: I like to do for myself. So that means I have to learn a bunch. And that means throwing myself to the mercy of the court (you).

At least I have a few things going for me: I’m an okay listener, I learn quickly, and I have a decent grasp of how stuff works (I’m a technical writer for the aftermarket automotive industry among other things). I’m also capable (I’ve driven across country and somewhat safely gone 100-plus mph in cars that I’ve built from scratch). I may be a fool but I’m no dummy.

I’m also a fundamentals kinda guy so that may be the best entry point. That said, I’ll end this introduction with a question: where should I start?

Thanks,

Chris

Jamie Hall

The best place to start is in many ways the simplest: how much heat will you need? In other words, do a room by room heat loss assessment for your house.

Once you have that, you can then see if radiant floors are feasible. They probably are, but it's best to check. Figure as a conservative value that the floor can deliver about 20 BTUh per square foot. You might be able to get more out of it, but might as well start low. Note that rugs reduce that. And wall to wall carpet is lethal...

Then one can start figuring how to install the system. But do that first.

Gordy

First step is a heat loss calculation. All design requirements pivot on a room by room heat loss calculation.

Gsmith

On an island in Washington state--what, besides wood, might be your alternate fuel source--is gas available, is there an oil delivery service on the island or by boat--Washington is kind of mile, could solar work for your--Washington also has pretty inexpensive electricity, could ground source heat pump powered electricity work? I'd start with possible fuel sources.

shelton

Thanks a bunch for the speedy responses.

Jamie and Gordy: I guess I must be half bright because I was working on heat-loss calcs. I figure this calculator isn't exactly precise but it should get me into the ballpark. Thoughts?

Gary: We have a few fuel options. Electricity runs about $.09KWH ($2.60/therm). We have natural gas at $.40/therm plus $4 monthly in the street. The gas company will bring it to a meter for free if we install a boiler/heater. I want a heater in the garage so gas looks like a good choice (but we'll address that when it's more appropriate).

Oil and LPG are prohibitively expensive and wood/pellet boilers are off the table for the reasons that we're sick of humping cordwood. So for the most part it looks like NG wins with electricity a fairly distant second (but that's a topic for a later debate).

Solar is off the table for cost reasons. We have good southern exposure but we also have a good-looking house that I wouldn't want to spoil with panels or tubes. We also have a newish roof so solar shingles/tiles are out of the question.

As for heat pumps, when I explained to my wife that they're really efficient, she said I could use the savings to hire a good divorce lawyer. She grew up on heated floors and radiators (Switzerland) so she's kinda spoiled.

flat_twin

If you have a smart phone or tablet, look for the Slant Fin heat loss app. It is very detailed but easy to follow.

Gordy

I would advise Trying other heat loss programs. uponor, taco,Slant fin. Taco is a wonderful site to learn more. Also caleffi has tons of information through the idronics segments to help you better understand hydronic.

Gordy

Once you have completed a solid heat loss. Then you will know how many btus a sf is needed for each room. This will then dictate. Boiler size, tubing centers, flow rates, and average water temperature.

Then it comes down to how well the existing structure lends itself for a radiant assembly.
Over the top. Sandwich with plates. Gypcrete ect.
Underneath. Staple up with plates, etc.


Keep coming back as you learn, and have question happy to help!

hot_rod

shelton said:

Thanks a bunch for the speedy responses.

Jamie and Gordie: I guess I must be half bright because I was working on heat-loss calcs. I figure this calculator isn't exactly precise but it should get me into the ballpark. Thoughts?

Gary: We have a few fuel options. Electricity runs about $.09KWH ($2.60/therm). We have natural gas at $.40/therm plus $4 monthly in the street. The gas company will bring it to a meter for free if we install a boiler/heater. I want a heater in the garage so gas looks like a good choice (but we'll address that when it's more appropriate).

Oil and LPG are prohibitively expensive and wood/pellet boilers are off the table for the reasons that we're sick of humping cordwood. So for the most part it looks like NG wins with electricity a fairly distant second (but that's a topic for a later debate).

Solar is off the table for cost reasons. We have good southern exposure but we also have a good-looking house that I wouldn't want to spoil with panels or tubes. We also have a newish roof so solar shingles/tiles are out of the question.

As for heat pumps, when I explained to my wife that they're really efficient, she said I could use the savings to hire a good divorce lawyer. She grew up on heated floors and radiators (Switzerland) so she's kinda spoiled.

If electricity is your fuel choice there are some air to water heat pumps on the market, it may qualify for rebates in your area. Here is a link to what is available for incentives.

http://programs.dsireusa.org/system/program?fromSir=0&state=WA

Here is the schematic from a friend in Upstate NY that uses an air to water hp for hydronics and some DHW.

shelton

Thanks flat_twin and Gordy for the other resources. I downloaded the Slantfin and will play with it tonight.

Hot Rod: well I guess I learned something else today (I wasn't aware of the air-water heat pumps). So my apologies Gary for assuming that you meant air-air pumps.

Not to get too far ahead of ourselves here but would the efficiency of the air-water heat pump bring the operation cost closer to that of gas? I understand that the increased inlet temperature reduces a gas boiler's efficiency (at least a condensing boiler anyway).

Gordy

With radiant floors, and your region I highly doubt return water temps will bring your efficiency of a mod/con down. They live for that type of emitter.

However the type of radiant floor assembly helps emensly.

Over the top is going to give the lowest water temps achievable verses under floor assemblies. Heat transfer plates also play a large role in getting those average water temps down.

Gordy

With your presenting costs I highly doubt the air to water heat pump will offer cheaper operating costs.

For 100,000 btus
Electric at .09 is 2.63
NG at .40 per therm (100k btus) .40 cents

however it comes down to future energy pricing also.

Air to water heat pumps can only produce about 120 swt max. Your radiant floor would most likely not require more than that. The other electric option is an electric boiler if you would like to go with electric.

shelton

Gordy said:

With radiant floors, and your region I highly doubt return water temps will bring your efficiency of a mod/con down. They live for that type of emitter.

Sweet.

Gordy said:

Over the top is going to give the lowest water temps achievable verses under floor assemblies. Heat transfer plates also play a large role in getting those average water temps down.

I intend to go over-floor with a homemade Uponor-style Quik Trak (a buck a square for materials compared to seven for premade appeals to me). Another reason to go homemade is the option to run a larger tube. We have an open room that's going to require numerous zones as it stands to keep tube length manageable. Cement board and porcelain tile goes over that. We have a few medium-sized rugs but no carpet.

As for heat-transfer plates, is that exclusive to under-floor or do I have to run some sort of metallic conductor if I go above-floor?

Gordy

I would use them on over the top also, especially where rugs will be used. They also help reduce stripping. Quality omega style plates. You can use smaller tubing 3/8 which is easier to work with, and keeps your build up a little thinner. You just have to manage loop lengths. 200' for 3/8. This keeps circulator sizing in the ecm circulator range.

shelton

Okay, I downloaded the Slant Fin app and input our house to the best of my ability. The house is a little unconventional as it has conventional 8' walls but a 12-12 roof that makes it a two-story building. The upper level is a loft that takes up half of the available space (it overlooks downstairs).

These are the pertinents:
*24-degree outdoor temperature (uncommon but it happens for a couple weeks at night
*70-degree indoor target temperature
*increasing wall area to compensate for roof pitch
*2x6 rafters and 2x4 walls

The calculator says the house requires 17,000btu. That seems a touch low to me. But this is a small house (1,300 or so square feet) built in the early eighties so it's fairly well sealed (dual-pane glass and all).

I suppose that low figure is somewhat consistent with our usage: We can stay comfortable from about 9am to about midnight during the heating season (October through late March) for a little more than a cord of Douglas Fir. According to people we know who also heat with wood, that's very little consumption. And that's keeping the house right at or slightly warmer than 70F.

I can further break down the loads by room if necessary. Thanks again for your guidance and patience.

Gordy

13 btus sf completely with in a RFH systems ability.

Make sure your wife understands your floors will NOT be warm, but mostly neutral. Which is by far better than cold, especially with tile. However your not in the same heating zone as Switzerland.

Maybe panel rads would be a better selection to suit your load, and keep the wifey happy use the RFH in rooms like the baths, and tiled areas. Panel rads have a faster response time also.

shelton

Gordy said:

Make sure your wife understands your floors will NOT be warm, but mostly neutral. Which is by far better than cold, especially with tile.

Actually the whole first level will be tile. That's why she's so adamant about it. Really the temperature of the floor doesn't matter so long as it isn't like an ice rink and keeps the room at our target temperature.

Gordy said:

However your not in the same heating zone as Switzerland.

Actually we're within about five or so degrees of the area where she grew up (outside Zurich). For the past week we were bouncing from 30 to 34 which was the same as at her parents' place. The mountains, yeah they're a LOT colder.

Gordy said:

Maybe panel rads would be a better selection to suit your load, and keep the wifey happy use the RFH in rooms like the baths, and tiled areas.

I'm totally open to panel rads upstairs as the floor temp won't be an issue (that's all going to be lino, cork, or wood). Well the upstairs bath will have tile but it's so small that I wouldn't object to using resistance heat to take the edge off the floor where we contact it and use a panel rad to bring the room up to temp. The level below it will be heated anyway so it won't get icy cold.

Here's the 574,000-dollar question: do panel rads operate at the same water temperature as the under-floor system? I hope they do because panel rads would be much easier to implement upstairs than a heated floor.

Thanks again,

c

Hilly

If you size your panel rads correctly you should be able to get the SWT to about the same as the radiant floor. It'll then come down to how large they have to be and will the fit the aesthetics and shape of the second level. I have a picture of your house in my head but don't know if it's anything like what I'm thinking. I have a crafty imagination. haha.

Gordy

Panel rads can operate at lower temps. However they need to be sized to allow for the lower AWT. Most manufacturers have outputs at various water temps. Couple them with trvs you got a nice emitter.

If bigger size doesn't work out for esthetic reasons just do a higher temp zone.

shelton

Hilly said:

If you size your panel rads correctly you should be able to get the SWT to about the same as the radiant floor.

I poked around the Myson site and saw some pretty encouraging figures. I also answered my own question about the efficacy of lower-temperature heat sources (Myson actually encourages it).

Hilly said:

It'll then come down to how large they have to be and will the fit the aesthetics and shape of the second level.

Size and aesthetics aren't an issue with the modern units. Our baseline is the Cadet baseboard heaters in my office and near our bed (I use the baseboard heat only during cold spells and only in my office). And anything looks better than those. My wife is used to radiators, growing up in Europe and all. While we were there for Christmas she even pointed out a few that she'd have just because she liked the way they look.

Hilly said:

I have a picture of your house in my head but don't know if it's anything like what I'm thinking. I have a crafty imagination. haha.

It's a cool looking house. It was built in '82 but everybody thinks it's the house from the farm that became our neighborhood.



And here's how it looked for the past week:

shelton

Gordy said:

Panel rads can operate at lower temps. However they need to be sized to allow for the lower AWT. Most manufacturers have outputs at various water temps. Couple them with trvs you got a nice emitter.

If bigger size doesn't work out for esthetic reasons just do a higher temp zone.

Yeah, this rad thing is going to make my life a lot easier on that upper level. As I mentioned in the post just after yours, size isn't an issue. I also like the idea of the faster response and the adjustable valves on the units themselves. We stay in my wife's childhood bedroom at her parents' place whenever we visit and it has a rad with a trv. It makes setting room temp a snap.

shelton

Okay, so my skepticism prevailed and I calculated our house as if it were two big rooms with doors and windows (which is pretty much what it is--the only walls are for a bedroom and two bathrooms). This time the Slant Fin calculator says 27,000BTU. Which is more consistent with what the other calculators say it should be.

If that's the case it means 20BTU per square foot. Which, correct me if I'm wrong, is well within the parameters of floor heat (and likely a combo of floor downstairs and radiators upstairs).

Am I all wet in thinking that a 1,300-square house will consume 27,000btu on a 24-degree day? (that's a super-extreme outside temp for us, BTW).

Gordy

Yes.

Gordy

Typically heat loss programs have a fudge factor 20% from real life. There is a reason though. They have no way of knowing how accurate the user is with their assumptions.

shelton

Gordy said:

Typically heat loss programs have a fudge factor 20% from real life. There is a reason though. They have no way of knowing how accurate the user is with their assumptions.

Margins are totally understandable but that's a 60-percent spread! Now am I safer going with the greater figure? In a general sense it seems it's better to have it and not need it than the other way around but how does that play with turndown ratio?

Now that we kind of have a good idea of how much heat I need, should I start considering boilers?

Thanks again,

chris

Gordy

GIGO. We can only count on you Shelton. Now if you would have said 100 k I know that's bs.

Gordy

It's 80's construction quite predictable.

Gordy

Yes to a modulating condensing boiler.

flat_twin

Beautiful home and property Chris. One cord of wood for the heating season isn't much. NG fired modcon with radiant shouldn't cost much to heat it.
The gas company is willing to bring service to the house at no charge just for hooking up? There's a huge benefit right there. Our small town just got NG last summer. Tap fee plus footage to the house was $2600 alone. Then add the cost of a NG boiler installation. Still well worth it.

shelton

flat_twin said:

Beautiful home and property Chris.

Thanks, mate. It was pretty scary when we bought it: hearing-aid beige and brown trim that hadn't been repainted since it was built 24 years earlier and we have lots of wind.

flat_twin said:

One cord of wood for the heating season isn't much.

No it's not but that's largely because we don't heat at night (don't want to get up to feed the fire). Surely we'd use more if we heated 24/7 as we will with the hydronic.

flat_twin said:

The gas company is willing to bring service to the house at no charge just for hooking up?

Yup. Lucky. To be fair gas is on our side of the street and it's probably 70 feet from the line to the house.

shelton

Okay, I found the discrepancies between the results in the Slant Fin calculator. I accidentally doubled up on a couple windows in one calculation and undervalued the exposed wall area in the other calculator. It now reads like so:

22,000btu if factoring room-by-room with the partition walls

24,100btu if factoring on two big open spaces with doors and windows.

At this point I think any further calculation will amount to tripping over mouse turds--this is down to like 10 percent. The generic online calculators say 30,000BTU but that's just based on a lot of assumed values. I trust the Slant Fin figures more.

I'm pretty confident with the btu values. What should I do next? And should I dedicate a new thread to this next phase?

Thanks for your help,

chris

billyboy

For high reliability, with low cost of install & maintenance, I would look hard at a Burnham ESC3 boiler.

billyboy

You will probably need a correctly sized indirect hot water heater. The ESC3 needs to run at high return water temperatures to prevent condensation (rot) in its cast iron heat exchanger.

Depending on your heat emitters, you probably will need to mix down your system water temperature.

If you go with a mod/con boiler, it has to run on high fire & high return water temperature to heat the indirect, it will not condense doing this and runs at about the same 85% efficiency as the ESC3 for domestic hot water. DHW could be a big % of your total use, depending on family size.

You could probably pump your entire system with only 2 pumps, I recommend Grundfos Alpha low wattage ECM type.

Gordy

With his system he should look hard at a mod/con.

Gordy

His load at design is only 24 k. He could use the low end modulation especially with low operating system temps of radiant floors, and panel rads. The smallest mod/con is still to big at 100% output.

billyboy

Copied from a post by Jason:
"Either boiler you choose needs to be sized properly. Even though I prefer mod/cons in any application I can argue the point both positive and negative on either side. I will start with the mod/con.
1. ODR is included, no extra charge. With most wireless sensor can be an option
2. Modulation, A mod/con boiler will reduce the input as needed. I have heard that a mod/con will operate in the lower half of the input 60% of the heating system
3. More important to properly size due to higher off cycle losses
4. Proper sizing gives lower turndowns for smaller zones
5. More expensive parts
6. More maintenance
7. Low return temps without worry, condensing a good thing
8. As water temperature increases takes a bigger hit on efficiency
9. Must be set up with a combustion analyzer
Outdoor air for combustion

Cast iron (ESC since OP mentioned it)
1. Need to be properly sized since
2.Full input only
3. ODR extra option
4. Can use wireless OD sensor, btw, same price as wired sensor when orderded with the ODR card, little known fact
5. less maintenace
6. Thermal mass and higher water volume a plus
7. Cannot return less than 110f, condensation bad
8. Starts with a lower efficiency but takes a smaller hit as water temperature increases.
8. Should be checked with a combustion analyzer

Maximize efficiency of both products
1. Proper size
2. Combustion air from outside
3. Do the math and calculate the high limit setting
4. Calculate the minimum boiler setting and set the ODR parameters including minimum boiler settings
5. Pipe the products per the I&O manuals that come with the products
6.Do not make too make small zones
7. Check incoming gas pressures whlie boiler is in high fire to meet spec's.
8. Don't over pump the system or boilers"

I will add:
Mod cons require yearly maintenance = more money
Mod cons cost MUCH more = more money
Mod cons fail more often & parts cost more = more money
Mod cons don't last as long = more money
Mod cons change design often requiring specialized technicians
that may be hard to find 10 years from now on an obsolete model, but don't worry about this as they probably won't last that long.

Gordy

Sooo your suggesting a boiler with 45k fixed output for a heat loss of 24 k at design? Because of Jason's post.

Let alone the proposed system that lends itself to a mod/cons liking. Producing dhw is a small amount of boiler time really in the heating season. Producing it at even 85% in the summer is far more efficient than a conventional water heater.

flat_twin

Chris, Did your house ever have central heat ? Is there a chimney? I don't see one in the pics other than for the wood burner. That would even things up for the cast iron vs modcon debate regarding installation costs. Over the last year I went thru this decision making process. The cost of chimney repair and a liner nearly made up the difference in the cost of the modcon boiler. Then I learned how well my emitters would work with it and it was an easy decision.

How are you currently making hot water? Electric storage tank? Are you considering an indirect water heater as well?

Gordy

People have to start really reading, and understanding the basis of the arguement in posts of a ci boiler vs mid:con comparison.

The ci boiler becomes more attractive to some (not me) ONLY when one can be selected to match the load, AND when the emitter requires a high swt.

When designing from scratch as with Chris's proposed system one can easily accomodate what a mod/con needs to get the highest performance it can deliver.

shelton

billyboy said:

For high reliability, with low cost of install & maintenance, I would look hard at a Burnham ESC3 boiler.

Thanks for the input and the suggestion. I appreciate the simplicity and potential ruggedness of an iron boiler and I don't mind the potential efficiency loss. But I think a mod-con might better serve my purposes better than an iron boiler for the reasons Gordy cited. Case in point, for the past few days we've been in the 40-to-45-degree range and unless something drastic happens we won't see anything cooler than mid-thirties at night until next October/November. That translates to a 30-degree indoor/outdoor differential which would require only 17K BTU. Come April we probably won't need to heat at all. Also another thing to consider: even though we burned our last fire yesterday morning, the interior temperature was 56 degrees this morning. The house really doesn't need that much heat.

Regarding chimneys. No, we don't have any beyond the one for the wood stove. And because of the house's very open plan I don't think we could install one very easily. A garage install is out of the question (already filled to capacity). Which leaves the crawlspace, an outdoor enclosure (that I'd have to build), or wall mounting above the washing machine. The trouble with the crawlspace is that the opening isn't all that big and it's in a kind of awkward location. These things make the wall-mount more appealing and from what I understand wall-mounting is easy with most mod-cons.

About the domestic host water. We're planning on keeping the electric tank, at least for the time being. With only two people in the house we don't use that much hot water (two showers and dishes daily).

I hope I addressed everything I needed to. I guess the pertinent question is whether we should keep this thread going or if I should dedicate a second one to the next step (which presumably is boiler selection). Ideas?

Thanks again,

chris

Gordy

It's easier when the discussion is continued in the same thread. Then everyone can follow From the beginning.