Electric Boiler
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- Start date
Highbeam
Well-known member
Where do you live? What is the desired interior temp? What is the insulation level?
Randy in Maine
Well-known member
For the record, I am a cheapskate and try not to pay too much for about anything.
Do you have access to any other fuels (like natural gas, propane, wood or waste oil) to heat the water?
Can you insulate the concrete block?
How warm are you trying to keep the building?
Do you have access to any other fuels (like natural gas, propane, wood or waste oil) to heat the water?
Can you insulate the concrete block?
How warm are you trying to keep the building?
Id like to keep it 55 to 60 Deg..
The Block are not Insulated.. I do not have Gas where I live and I hate cutting Wood so Im kinda a stuck with Electric..
I want to try the Electric and if its too costly I may be forced to go with a Wood and Coal Outside Boiler
The Block are not Insulated.. I do not have Gas where I live and I hate cutting Wood so Im kinda a stuck with Electric..
I want to try the Electric and if its too costly I may be forced to go with a Wood and Coal Outside Boiler
Randy in Maine
Well-known member
I pay about 12 cents a kilowatt hour for electricty. Heating water (even to 125º F) for the radiant floor heat made no sense to me long term. Just too much money for me. Instead I invested in a condensing boiler fired by propane (mine is a Baxi with about 126K BTUs but there are plenty of other good ones out there) and heats not only my garage to 55º but also my house of 1000 square feet (to 66º) and my wife's stained glass studio of 300 square feet (to 60º) in 3 zones fired off the Baxi. It also does all of my domestic hot water. My garage and house are all pretty tight and with R-40 or better everywhere and it can get colder and windy here than in Philly.
55º in the garage is very nice and the floor is about 62º. 66º is the house is pretty good also as the floors are about 71º, I turn othat stuff on at Thanskgiving and off about April.
My other goal was to keep fire and sparks out of the new garage which is the other reason I went that way.
I expect to heat the whole place of all 3 zones for about $1500 a year (500 gallons of propane x $3 a gallon).
If you are on a tight budget, you might look into a propane gas hot water heater all set up, but I don't know how long that would last in heating the whole place. I think my boiler was about $3K all installed.
55º in the garage is very nice and the floor is about 62º. 66º is the house is pretty good also as the floors are about 71º, I turn othat stuff on at Thanskgiving and off about April.
My other goal was to keep fire and sparks out of the new garage which is the other reason I went that way.
I expect to heat the whole place of all 3 zones for about $1500 a year (500 gallons of propane x $3 a gallon).
If you are on a tight budget, you might look into a propane gas hot water heater all set up, but I don't know how long that would last in heating the whole place. I think my boiler was about $3K all installed.
Highbeam
Well-known member
Randy, you're not saving money with your boiler. In fact you're wasting it and you should have gone with electric.
Electric at 12 cents costs 35.16 per MBTU.
Your baxi boiler has an afue of 92.5%, I'll round up to 93% and at 3$ per gallon you are paying 35.81 per Mbtu.
Also remember that you paid big money for that boiler, installation, and now the hassle of propane delivery when you had electric already plumbed to your house.
I thought you were a cheapskate?
Electric at 12 cents costs 35.16 per MBTU.
Your baxi boiler has an afue of 92.5%, I'll round up to 93% and at 3$ per gallon you are paying 35.81 per Mbtu.
Also remember that you paid big money for that boiler, installation, and now the hassle of propane delivery when you had electric already plumbed to your house.
I thought you were a cheapskate?
Yes I plan to mount them on the Wall.. Should I buy 2?
How high can I mount them on Wall?
jvitez
Well-known member
You need to insulate the block wall! It's a huge heat sink draining away heat. Put at least 1.5 inches (2" would be better) of extruded polystyrene insulation (R-5 per inch) on the exposed block. Examples are Styrofoam or Celfort. Cover it with drywall. It will cut down your heat loss substantially.
You might want to consider putting foam board over the studs on the inside if your outside walls are finished. This eliminates conductive heat loss through the studs. Your R-13 is probably about R10-11 if you factor in the studs.
Check out this seller (no affiliation).
http://www.radiantmadesimple.com/index.php
The two sizes they have are 7 and 11 kW. They say the max is 1800 sq ft for the 11 kw unit, but they're in Minnesota. What are the winters like in Pa.?
An 11 kw boiler for your garage is only 6.1 watts/sq ft which isn't much, but even if it runs 100% of the time on the coldest day of the year and holds your desired temp it's the right size.
You really need to get a proper heat loss calculation to be sure. Do it with your current set up, and do it again adding insulation to the exposed block. See how many less btu's you'll need. There are on-line calculators available FWIW. Here's a basic one for residential construction, not garages as an example:
http://www.ouellet.com/heat-capacity-calc.aspx
You might want to consider putting foam board over the studs on the inside if your outside walls are finished. This eliminates conductive heat loss through the studs. Your R-13 is probably about R10-11 if you factor in the studs.
Check out this seller (no affiliation).
http://www.radiantmadesimple.com/index.php
The two sizes they have are 7 and 11 kW. They say the max is 1800 sq ft for the 11 kw unit, but they're in Minnesota. What are the winters like in Pa.?
An 11 kw boiler for your garage is only 6.1 watts/sq ft which isn't much, but even if it runs 100% of the time on the coldest day of the year and holds your desired temp it's the right size.
You really need to get a proper heat loss calculation to be sure. Do it with your current set up, and do it again adding insulation to the exposed block. See how many less btu's you'll need. There are on-line calculators available FWIW. Here's a basic one for residential construction, not garages as an example:
http://www.ouellet.com/heat-capacity-calc.aspx
Kinda irrelevant On height as the extra height of the heater will only add a few feet of pex tube.
Using two heaters may allow you a cheap way to zone things out without needing any kinda spendy mixing or elaborate manifolds.
Just keep in mind that your block wall has the same R value as a single pane of glass. Also, did you use any expansion material between the slab and that block wall?
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I did use Expansion around the Slab.. Im going to look into having the Blocks foam filled. I heard of a Company that does Commercial Buildings.
Winters in Pa average temp is in the 20s and 30s once in a while it dips down into the teens for a couple Days..
Already have my Walls covered so cant do much with the R-13
Seisco is a quality unit to buy?
Winters in Pa average temp is in the 20s and 30s once in a while it dips down into the teens for a couple Days..
Already have my Walls covered so cant do much with the R-13
Seisco is a quality unit to buy?
rwcarnut
New member
I have a similar set up 32x50 with 6 loops under 300 ft each, I installed a 18kw thermolec. I went with SS pumps and boiler due to using regular 1/2 pex and was advised not to use cast boiler or pump. Guess I could have spent the money on the O2 barrier pex from the start but the way I look at it the SS was not cheap but should last forever?
BadgerBoilerMN
Well-known member
The vendor should size the boiler for you. Otherwise hire someone to do it right. Insulating the sidewalls is a must.
Randy in Maine
Well-known member
OK I just got the new electric bill. 437kw for $64.78. Propane was $2.69 per gallon. My Baxi is about 98% afue.
I still say electric is no deal.
BadgerBoilerMN
Well-known member
There are no 98% AFUE boilers. Baxi may claim 98% thermal efficiency, but it is not the same number. You can reasonably use .95 as a multiplier again the full Btu value of the propane.
At the current rates it appears to be wash. You did spend 3 times as much of the condensing boiler as you might for an comparable electric and you have to have the Baxi serviced yearly to maintain any efficiency or reliability.
I know it hurts. I have been installing condensing boilers for 25 years now and had to install an electric boiler because of the math. Fortunately we are all smart enough to use hot water, so we can always change our minds.
At the current rates it appears to be wash. You did spend 3 times as much of the condensing boiler as you might for an comparable electric and you have to have the Baxi serviced yearly to maintain any efficiency or reliability.
I know it hurts. I have been installing condensing boilers for 25 years now and had to install an electric boiler because of the math. Fortunately we are all smart enough to use hot water, so we can always change our minds.
Highbeam
Well-known member
I went to the baxi website and they claimed 92.5% afue. I would do it again and post a link but we can give you the benefit of the doubt and go for 95%.
So you are paying 14.8 cents per kwh and 2.69 per gallon. 100% efficiency for electric resistance and 95% for your boiler.
Your costs are 43.36 for electric and 31.43 for propane per mbtu so yes, for fuel costs alone the propane is cheaper.
Randy in Maine
Well-known member
Not to side track this thread too much more, but what is the suggested boiler water temperature to be run through the 1/2" radiant floor tubing most efficiently?
I have mine set at about 125º F or 50º C, but of course the floors don't get nearly that warm in any of the 3 zones.
Generally my floors are closer to about 70-72º F or so in the house and a bit less in the garage.
I have mine set at about 125º F or 50º C, but of course the floors don't get nearly that warm in any of the 3 zones.
Generally my floors are closer to about 70-72º F or so in the house and a bit less in the garage.
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Randy thats kind of a trick question, take a look at your Delta T to help you decide whats best. Let it run for a few hours and see how close it gets with the settings that you have, if its not close you may need more temp in, or a faster pump speed.
I tried it a few ways, hot and fast, then low n slow. It runs a bit longer when I send 115º into the slab versus 165º or so, but the heater is not drawing as much current at 115º and I would tend to think my heater will live longer that way.
I tried it a few ways, hot and fast, then low n slow. It runs a bit longer when I send 115º into the slab versus 165º or so, but the heater is not drawing as much current at 115º and I would tend to think my heater will live longer that way.
BadgerBoilerMN
Well-known member
OK.
The delta T determines the thermal gradient of any given radiant panel i.e. the surface temperature from one end of a loop to the other (highly dependent on pattern).
More to the point, the best boiler temperature is always the lowest temperature that your boiler will tolerate. With condensing boilers the closer to freezing the return water temperature, the more efficient the heat transfer and recovered condensate.
It is easy to get comfort and economy mixed up. The better insulated the house, the lower the design temperature (the warmest water temperature needed to meet the heat load on the coldest day of the year). In a newer home a radiant floor will rarely feel warm unless you are at design conditions. The point is really that the floors are not cold, usually about 66°F, so be happy.
PS With a condensing boiler stretching the delta T (within parameters) may indeed lower return water temperatures and consequently raise thermal efficiency but stretching the system delta T with an electric boiler will only save on the parasitic energy used by the pump...a few dollars in a season.
The delta T determines the thermal gradient of any given radiant panel i.e. the surface temperature from one end of a loop to the other (highly dependent on pattern).
More to the point, the best boiler temperature is always the lowest temperature that your boiler will tolerate. With condensing boilers the closer to freezing the return water temperature, the more efficient the heat transfer and recovered condensate.
It is easy to get comfort and economy mixed up. The better insulated the house, the lower the design temperature (the warmest water temperature needed to meet the heat load on the coldest day of the year). In a newer home a radiant floor will rarely feel warm unless you are at design conditions. The point is really that the floors are not cold, usually about 66°F, so be happy.
PS With a condensing boiler stretching the delta T (within parameters) may indeed lower return water temperatures and consequently raise thermal efficiency but stretching the system delta T with an electric boiler will only save on the parasitic energy used by the pump...a few dollars in a season.
Ok so I had a Company come out and insulate My Block..
They drilled holes in the block and pumped foam into them.. They claim they are a R-15 now. Is this true?
I also bought a 12 KW Argo Boiler.. Is this brand a good one?
I hope this is a good one cause I have a guy that started hooking it up Today
They drilled holes in the block and pumped foam into them.. They claim they are a R-15 now. Is this true?
I also bought a 12 KW Argo Boiler.. Is this brand a good one?
I hope this is a good one cause I have a guy that started hooking it up Today
matouse3
Well-known member
I hate to be skeptical, but do your blocks have some type of thermal break in them? I can't see how they would instantly become R15 with just foam pumped into the hollow spaces when you still have a straight run of cement from the inside to the outside spaces.
Good luck with that boiler, I'm sure its a good one. Keep up updated on how it performs.
BadgerBoilerMN
Well-known member
It is not boiler or the foam that matter so much as the guy behind the wrench.
In any case. A little late now.
Best of luck and Merry Christmas.
In any case. A little late now.
Best of luck and Merry Christmas.
CARS
Well-known member
When my in-floor was done, I didn't have a clue and apparently either did my heating guy. Small town, one plumbing and heating guy around...
I knew from reading up on it that I needed 2' of foam under the slab and down along the footing (stem wall??). What I didn't know (or think of) was that we needed a thermal break between the slab and the couple feet of concrete sticking up out of the ground
I fired up the system in Oct. that year and within a month I used over 1/2 of my 500 gal. LP tank WTF!
So the installer called in a rep from the company he gets supplies and support from, they change a couple of things like mixing valve location, pressure in the system, cut the antifreeze a little, etc. to fine tune it. It helped, but I used a ton of LP that first winter. I noticed one important thing that winter though. The snow was melting a foot away from the building!
The foundation wall was pulling all the heat from around the perimeter slab.
Well, it's a little late now to change anything inside, so the next summer I dug down along the outside of the wall to get 4'x8' sheets of 2" foam on the foundation wall. I beveled the top edges, added mesh tape, and stuccoed the foam to make it look "good".
The next winter, with the fine tuning and foam added, I used half the LP as the previous year even though it seemed like we had a longer heating season. Snow didn't melt away from the building (I even pushed snow against the building with a plow thinking that it would be a wind block )
So, Maybe you too can figure out a way to insulate the outside of your block wall. Sure it will still want to pull heat into the block but most of it will be re-directed into your heated space.
jeez I am long winded this morning. I better get some work done
I knew from reading up on it that I needed 2' of foam under the slab and down along the footing (stem wall??). What I didn't know (or think of) was that we needed a thermal break between the slab and the couple feet of concrete sticking up out of the ground
I fired up the system in Oct. that year and within a month I used over 1/2 of my 500 gal. LP tank
WTF!So the installer called in a rep from the company he gets supplies and support from, they change a couple of things like mixing valve location, pressure in the system, cut the antifreeze a little, etc. to fine tune it. It helped, but I used a ton of LP that first winter. I noticed one important thing that winter though. The snow was melting a foot away from the building!
The foundation wall was pulling all the heat from around the perimeter slab.
Well, it's a little late now to change anything inside, so the next summer I dug down along the outside of the wall to get 4'x8' sheets of 2" foam on the foundation wall. I beveled the top edges, added mesh tape, and stuccoed the foam to make it look "good".
The next winter, with the fine tuning and foam added, I used half the LP as the previous year even though it seemed like we had a longer heating season. Snow didn't melt away from the building (I even pushed snow against the building with a plow thinking that it would be a wind block
)So, Maybe you too can figure out a way to insulate the outside of your block wall. Sure it will still want to pull heat into the block but most of it will be re-directed into your heated space.
jeez I am long winded this morning. I better get some work done
Randy in Maine
Well-known member
X2 on what they said.
I used 2" thick rigid foam on the inside of my house crawl space to about 2' below the outside ground surface and it has really helped keep it nice down there. No more pipe freezing. My heated floors have a radiant silver floor barrier, insulated with R-19 and with 1" foamboard so that the heat from the floors are all directed upwards.
On my new garage, I also used the same 2" rigid foam on the inside walls to give me a thermal break between my heated floor and my unheated walls and it has worked very well. I put mine to the bottom of the heated slab before they poured the concrete. I then trimmed mine out with 12" tall pine and 3" pine ledge on top of that so that I would not have to look at the silver foam for the next 30 years. My walls are also all finished pine so it fits in pretty nicely.
I used 2" thick rigid foam on the inside of my house crawl space to about 2' below the outside ground surface and it has really helped keep it nice down there. No more pipe freezing. My heated floors have a radiant silver floor barrier, insulated with R-19 and with 1" foamboard so that the heat from the floors are all directed upwards.
On my new garage, I also used the same 2" rigid foam on the inside walls to give me a thermal break between my heated floor and my unheated walls and it has worked very well. I put mine to the bottom of the heated slab before they poured the concrete. I then trimmed mine out with 12" tall pine and 3" pine ledge on top of that so that I would not have to look at the silver foam for the next 30 years. My walls are also all finished pine so it fits in pretty nicely.
BadgerBoilerMN
Well-known member
"I dug down along the outside of the wall to get 4'x8' sheets of 2" foam on the foundation wall. I beveled the top edges, added mesh tape, and stuccoed the foam to make it look "good".
The next winter, with the fine tuning and foam added, I used half the LP as the previous year even though it seemed like we had a longer heating season."
Now this is a good save and why we always get involved in the insulation and general construction before the job starts. A proper heat load and review of the plans goes a long way in the right hands.
Well done.
The next winter, with the fine tuning and foam added, I used half the LP as the previous year even though it seemed like we had a longer heating season."
Now this is a good save and why we always get involved in the insulation and general construction before the job starts. A proper heat load and review of the plans goes a long way in the right hands.
Well done.
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I took 1" foam board from footer up to ground level on outside of My block before I back filled.. 3 walls of my Garage are 3 blocks out of the ground. the front which is 32' wide is the only wall with 6 blocks out of ground..
I tried to have a Company do mine but no one in My area that does the floor heat in a non commercial building.. I called half of dozen company's couldn't even get them to come out because of size and being non commercial.
I waited a Year to get the concrete poured because of it.. So My concrete guy helped Me with laying tubing and Manifolds.. I have a local Plumber hooking up My boiler He's not that experienced with the floor heat so Im trying to learn
I tried to have a Company do mine but no one in My area that does the floor heat in a non commercial building.. I called half of dozen company's couldn't even get them to come out because of size and being non commercial.
I waited a Year to get the concrete poured because of it.. So My concrete guy helped Me with laying tubing and Manifolds.. I have a local Plumber hooking up My boiler He's not that experienced with the floor heat so Im trying to learn
BadgerBoilerMN
Well-known member
That is a sad state of affairs. One of my local plumbing and heating distributors recently told me of a plumbing contractor who complained of the lack of work. When the distributor asked him why he didn't do radiant floor heating he said; "I don't know anything about that stuff".
After I spent 5 years traveling around 5 states trying to convince heating contractors that it would heat homes, shops...even melt snow, the results after 20 years effort are disappointing.
We start with a proper drawing of the building with foundation details, the most important of which - as demonstrated here - is the perimeter insulation. It is the temperature differential that drives heat out of the building in general but out of a radiant slab heated building in particular. While you may have a 40° temperature reading in a building heated to 50° ambient at 5ft. Once you heat the floor to say 60°F you have more to worry about.
Here in Minneapolis I was called out to consult on a then recent installation of a new radiant slab in an older home. The contractor wanted to show me the flowers (January) growing just outside the foundation wall. You could clearly see the flowers through the floor-to-ceiling window. The new indoor radiant slab was nicely snow melting 1.5 ft. from the perimeter.
It seems the homeowner's fuel bills had gone up after the new snow melting...I mean radiant slab, had been installed without the benefit of perimeter insulation. As described here, we dug up the foundation wall and insulated with great success.
The point sometimes missing in poor radiant floor heating design is the most critical; the insulation R-value and placement. Naturally the R-value of the slab insulation will change with climate, but insulation placement is really straight forward. Wherever the elevated temperature of a building meets the outdoors; insulate.
We get many calls to design systems and to diagnose radiant floors that are burning too much fuel. Our first questions are to the frost line in the area we are working. When specifying insulation note that frost does not care where it goes, so insulating out from the slab, straight down or in from the perimeter, to the frost line, will work equally well as long as the end of the slab is not exposed.
I you have a pole shed, we have found the easiest and most effective way to insulate the slab is to insulate the inside of the forms capping the ends and setting a sheet of XPS 4 ft. around the perimeter at minimum depending on indoor and outdoor design temperatures.
After I spent 5 years traveling around 5 states trying to convince heating contractors that it would heat homes, shops...even melt snow, the results after 20 years effort are disappointing.
We start with a proper drawing of the building with foundation details, the most important of which - as demonstrated here - is the perimeter insulation. It is the temperature differential that drives heat out of the building in general but out of a radiant slab heated building in particular. While you may have a 40° temperature reading in a building heated to 50° ambient at 5ft. Once you heat the floor to say 60°F you have more to worry about.
Here in Minneapolis I was called out to consult on a then recent installation of a new radiant slab in an older home. The contractor wanted to show me the flowers (January) growing just outside the foundation wall. You could clearly see the flowers through the floor-to-ceiling window. The new indoor radiant slab was nicely snow melting 1.5 ft. from the perimeter.
It seems the homeowner's fuel bills had gone up after the new snow melting...I mean radiant slab, had been installed without the benefit of perimeter insulation. As described here, we dug up the foundation wall and insulated with great success.
The point sometimes missing in poor radiant floor heating design is the most critical; the insulation R-value and placement. Naturally the R-value of the slab insulation will change with climate, but insulation placement is really straight forward. Wherever the elevated temperature of a building meets the outdoors; insulate.
We get many calls to design systems and to diagnose radiant floors that are burning too much fuel. Our first questions are to the frost line in the area we are working. When specifying insulation note that frost does not care where it goes, so insulating out from the slab, straight down or in from the perimeter, to the frost line, will work equally well as long as the end of the slab is not exposed.
I you have a pole shed, we have found the easiest and most effective way to insulate the slab is to insulate the inside of the forms capping the ends and setting a sheet of XPS 4 ft. around the perimeter at minimum depending on indoor and outdoor design temperatures.
theoldwizard1
Well-known member
WOW !
Flowers, in January, in MN ! Amazing !!!
Just curious. In MN, how many inches of XPS do you typically recommend ?
BadgerBoilerMN
Well-known member
2" is common all over, but north of the cities it should really be 3-4.
BadgerBoilerMN
Well-known member
WOW !
Flowers, in January, in MN ! Amazing !!!
Just curious. In MN, how many inches of XPS do you typically recommend ?
OK, maybe it was Feb. and they were crocus', but there was snow on the ground.
So if I dig around the outside of the building I should put 2" foam board down to the footer? Or below the outside of the footer?
I may do this next Fall if My heat doesn't work properly..
So if it doesent melt snow around My building I should be OK?
I may do this next Fall if My heat doesn't work properly..
So if it doesent melt snow around My building I should be OK?
BadgerBoilerMN
Well-known member
If you have a radiant slab with the perimeter lacking insulation it is advisable to insulate to the bottom of the footing as this is usually also the frost line for your area.
You don't need to melt snow to prove you are losing heat to the outside witnessed by one of my recent snow melting systems that would not drive the walk above 32° but worked the boiler at what appeared to be full-fire for about 10 hours (operator error).
You don't need to melt snow to prove you are losing heat to the outside witnessed by one of my recent snow melting systems that would not drive the walk above 32° but worked the boiler at what appeared to be full-fire for about 10 hours (operator error).
cork
Well-known member
MJPPED any updates to this thread ? Im looking into electroc boilers for my radiant sysrem.