Outdoor Wood Furnace Info
All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: capon3 on August 29, 2011, 06:10:34 PM
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I just purchased a Legend L-4135 OWB, and I need a little advice on insulating the underground pipes. I plan on running 2 one inch pex pipes in the foam insulation sleeves and then wrapping that in HVAC bubble wrap and then putting that in corrugated drain tile. The run will be approximately 90 feet to the basement wall. Also do I need a separate heat exchanger to heat domestic hot water? Thanks in advance for your help.
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hmm..... I think if you shop around a little bit you can actually buy the line cheaper than you can make it.. it will be much better stuff as well. I have seen a lot of people try to do what your doing here and its often more headache than its worth.
things to keep in mind.
1. the insulation in triple wrap is not bubble wrap, it is often a product called prodex. Prodex has an r value nearly 3 times that of bubbe wrap at 15.67, and its only 5mm thick.
2. pulling it through without damaging your insulation, thats hard to do.
Now as far as your heat exchanger for your hot water, I will reccomend you getting a 20 plate heat exchanger with 1" mpt fittings. It will make all the hot water you can ever use and will not allow the water get hot enough to cause a scald or anything like that as other models may do.
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oh, and about the flat plate exchanger. it's easy as pie, just splice into the supply line at your hot water heater, run the supply line into one side of the plate, come out the other port on the same side, and go right back to the supply line you spliced into thats feeding your hot water tank. the plate exchanger's other 2 ports will be occupied by your furnace lines, it will come from your furnace and go to your plate exchanger first, and then on to your ductwork/plenum unit.
no moving parts, no valves, nothing. it's simple. you dont have to change anything about how your hot water heater works either. Only now instead of your hot water tank's supply line supplying 50 degree water to the tank, it will be going in at around 120-135 and never have to be heated. It turns your hot water heater into a storage tank .
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AMEN to heating the 50F water before the HWH and turning into a storage tank! :thumbup:
Wife can't wait for winter. We have lived here 19 years and she never said that once before.
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oh, and about the flat plate exchanger. it's easy as pie, just splice into the supply line at your hot water heater, run the supply line into one side of the plate, come out the other port on the same side, and go right back to the supply line you spliced into thats feeding your hot water tank. the plate exchanger's other 2 ports will be occupied by your furnace lines, it will come from your furnace and go to your plate exchanger first, and then on to your ductwork/plenum unit.
no moving parts, no valves, nothing. it's simple. you dont have to change anything about how your hot water heater works either. Only now instead of your hot water tank's supply line supplying 50 degree water to the tank, it will be going in at around 120-135 and never have to be heated. It turns your hot water heater into a storage tank .
I have a 20 plate coming in the mail. I was planning on installing it on the outgoing side of the current tank and turning the tank off when the furnace is running. Thoughts on this as opposed to the intake side? Would the tank not still heat occassionally to maintain the temperature? I have a mixing valve too so the water will not be too hot. Seemed that everyone recommended that soince the boiler could go as high as 180ish.
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I can give you a number of reasons why it's better to go in the intake side.
#1 send the mixing valve back, you wont need it. look at it like this, if its on the intake side, the plate exchanger may only hold 1/2 gallon, thats probably an overstatement, so only 1/2 gallon would be as hot as your furnace water, and by the time it goes into your tank and mixes with the 130 degree water. You wont know the difference.
#2 lets say your stove has a problem, wood doesnt fall down right, air vents get plugged up, been a long time since a fill up. the water temp drops to 120 or so in your boiler and its time for you and your family to get ready for work.. Guess what, no hot water. If you would have used your hot water tank as a storage tank, you would still have 50 gallons of hot water ready for immediate use.
#3 if the water entering the tank is 130 degrees and your tank is set on lets say 120, it will never have to kick on. and the more hot water you use in the home is the less likely it would ever kick on. hot water tanks today are insualted very well and use very little heat.
#4 leave your hot water tank on, ive ran mine both ways just to see if it makes a difference and it does not. but in the occassional circumstance where your stove gets cooled down, it will eliminate the case of this happening: stove drops to 100-120, your wife takes a shower and pulls in 80 degree water, it's not to hard for the electric to make up the difference and it keeps "anyone" later from having to take a cooler than normal shower.
Sooo........ Just leave it on, it makes for more consistant heating of water if something messes up.
I hope this is enough reason to make you want to put it on the intake side as there are no real advantages to putting in on the exhaust side. On the exhaust side you will have to run that mixing valve and then you'll have all the problems we talked about above.
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:post: I second that recommendation!
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Before you go buy a domestic water heat exchanger check with Legend or your dealer. I though they came with a domestic coil installed in the boiler.
The negative is that the hot water has some 'lag time' but you can overcome that by circulating it thru your water heater?
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Before you go buy a domestic water heat exchanger check with Legend or your dealer. I though they came with a domestic coil installed in the boiler.
The negative is that the hot water has some 'lag time' but you can overcome that by circulating it thru your water heater?
that may be an option on the legend. even if it were on my stove I would still use a 20 plate, half the lines to run underground, and once again you dont have to use mixing valves and all that stuff to keep from getting scalded.
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Before you go buy a domestic water heat exchanger check with Legend or your dealer. I though they came with a domestic coil installed in the boiler.
The negative is that the hot water has some 'lag time' but you can overcome that by circulating it thru your water heater?
I not use it either. The cost of the pipe usually is more than a plate costs.
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It does have the domestic hot water coil, but I was thinking the same thing that it would be cheaper to get a plate heat exchanger than buying the pipe.
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Somehow a word disappeared from my last post.
How many feet from the house are you going to put the boiler and what kind of insulated pipe are you planning on using? If it is close it might be worth trying it and run it into the tank the same way as Scott suggested running the plate. That way you don't get the lag.
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my stove is 250 feet from the house i would guess when i fire up that stove in the fall (i don't turn the pump on until the stove is up to temp) it takes about 1 to 1 1/2 minutes untill the lines in the house feel too hot to touch. If you had to wait 1 minute for the water to get from your heat coil in the furnace to the house each time you turned on theh hot water tap pluse the time it normally takes to get through your house pipes i would guess you are waisting a lot of water. if you pay for this water that sucks. if you however are paying to run your pump to heat your home 24/7 allready then a plate exchanger in my mind is the way to go.
if you install lines big enough to run a header system then you have all you need for multiple "appliances" my little taco 0011 has been running 11 years and pushing water to the furnace..a rad in my fireplace...and the domestic exchanger i built.
it also feeds my floor heat but that does have its own circulation pump and there is a rad on the return from the hot water coil to heat the basement if needed
just my 2 cents worth
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Yeah if you have the DHW pipes completely separate from the boiler lines it you will have to run a lot of water before it gets hot.
The 4 line insulated pipe I sell has the pipes in 2 pairs. Each pair is separated so you will get some heat transfer between the pex that should keep the water in the lines hot.
If it is a short run it might be worth it but it adds over $1 per foot to the pipe cost.
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capon3-
Do yourself a favor and definitely install a mixing valve in your application. There are times that you may end up with a heater nearly full of water that will be potentially hot enough to scald, and if you have small children running around in your home from time to time the last thing you need is the extra worry associated with water being hot enough to scald. My younger brother is a home inspector here in Mi. and he said he recommends to potential home buyers to have mixing valves installed in their future homes by the sellers. He couldn't imagine a licensed contractor not putting one in with either a plate exchanger or a tube exchanger set-up. There are times when my water gets up to 155* in my heater, which is plenty hot to do some serious damage. A mixing valve also makes your heater think it's bigger than it really is by keeping a constant supply temperature to items such as your washing machine and dishwasher. Check with local codes and I'll wager a mixing valve is required in your state. Other than that, sounds like you are on the right track. We like pictures!
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May I ask you how you think the water is going to keep getting hotter using a plate exchanger?????
if the water is in the supply line it cant sit and circulate like it does if you have a sidearm heat exchanger.
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young children can recieve 3rd degree burns in under 4 seconds from hot water that is above 120 degrees F That is almost the time it takes a child to react to the feeling of the water. us old folks dont burn quite so fast but why would you take the chance with your children? i do believe that a lot of new taps in the home have these mixing valves built in but they too can fail, why not have a backup right on yoru tank?
if you use a side arm or a plate exchanger you have the potential of storing water in your hot water tank or even if you are on demand right from your plate exchanger, the possability of your hot water at your tap being 1 or 2 degrees below your OWB temp is very high. lets say your OWB is at the top of its cycle and you have it set for 180 (factory setting in most cases) if you use a blower fed stove and it reaches 180 and shuts of the air supply and your stove is not drawing heat for your home it is possable for the OWB to climg another few degrees before the gasses burn off or die down from lack of air. so lets say your stove went to 183 now your pump is cycling this 183 water through yoru domestic water heater at this temp because at this time your furnace rad does not need heat, yoru child turns the tap on and then decides to do something like take thier shirt off or anything that may take a few seconds..now while they do this the water is running..when they decide its time to wash thier hands they stick them under the tap and they put them right in to that 180 or better water...ouch! poor kid...put on the mixing valve or turn your OWB down to under 120 and then you likely wont heat your house...PUT ON THE MIXING VALVE i t will also give you a nice steady stream of "hot enough water"
lets also look at the other scenerio..you have no mixing valve and you are one of them people who take long long showers.. you start out with 180 degree water so you have the cold turned open a long way to cool it to comfortable...as the OWB temp cools to "kick in temp" your hot water at the tap also cools and you are turning the cold off as you shower to maintain the heat you like..this goes on until your shower is done or if you stay long enough as your OWB recovers you are turning the cold back open to maintain your water temp...a lot of work for a shower....Put in the Mixing Valve and enjoy trouble free hot water...your wife and kids will love you for it
i guess that was a long winded one...my 15 cents worth..lol
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You would have to have a line in the bottom of the tank and out the top to make the water start a convection current, like a side arm does. I have never ever seen a water plate exchanger make the tank water go over what it normally runs, I checked it periodically with a heat gun and it was always the same
within 2-3 degrees
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i agree you will not create the syphon effect of a sidearm but if you have a tank full of hot water at say 120 (safe for children)in your domestic tank and you are delivering to that tank 180 from your OWB the temp in the domestic tank has to go up, say it even only goes up 5 or 6 degrees ..the first time the child goes to the bathroom and washes his or her hands the water is safely at 120 the next time they go maybe momma has been doing laundry and she is filling the washer with 15 or 20 gallons of hot water so now your domestic tank just recieved 20 gallons (possably half of it's capacity) and the water temps is now 125 or even higher remember the last time the child used the tap it was fine, they are not going to test it this time they are just gonna shove their tender skin under there..i still vote fore safety...mixing valve
again that is only my opinion...i have enough things to worry about besides my grandchildren hurting themselves under my taps...i didn't used to have the mixing valve myself..but i have for the last couple of years.
do i really need it...maybe and maybe not, but it is a safety device and i feel if it was not needed it would have never been offered
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What if.....
You do not fully turn off your hot water faucet? If it's leaking a couple gph, what will that do to your tank temperature after you get back from working a 16 hr. double shift? (your boiler temp is 180*)
What if.....
A hot water faucet develops a leak, or maybe one of your solder joints starts squirting, or a pex clamp decides it's time to start leaking and you do not notice it? The leak amounts to maybe 5 or 10 gph. Where will your tank temperature be after an 8 hour shift?
Now.....
Lets say your wife's daycare children, or your child, or your elderly parent or grandparent decides to wash up for dinner KNOWING that turning the hot water on only will yield the perfect temperature for hand washing. Your water in your tank is now up to 140* or more. What is going to happen?
You come across as a very intelligent man. When you do an install, incorporate a mixing valve. If the home owner does not want one, make him sign a waiver to protect yourself from future legal issues.
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Hey martyinmi, thats a good point.. One I had never thought of, I didnt mean to sound offensive in asking but I sure aint against learning something new. lol
I see what your saying though, if someone was to leave a faucet barely cracked on hot and it was slowly pulling the water through it could potentially have more time to heat the water and pull in some really hot water into the water tank.
One thing that amazes me is the different markets.. I can see that the folks in the northern markets really dot there i's so to speak. Where as people in my market are more after the cheapest way possible to do anything, occassionally you do run across someone here who wants to go the extra mile, but it is rare! Same way when we start talking efficiency, folks in the north seem really interested, and folks here say oh i got plenty of wood, all i need to know is will it heat my home!
I agree with your idea about the waiver, I think I should come up with a waiver for safety that covers anything to do with the system actually.
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Scott-
Are you having a harder time selling OWB's now than you did a few years back? Up here, we have lumber companies, hardware stores, etc. selling nearly all the brand name OWB's. They rarely comply with their obligations to the manufacturers, and because they buy in such large quantities, they can sell much cheaper than the small time dealers can. I have a few friends who are dealers, and they say they can see a time in the not too distant future where they won't be able to make anything from the boiler sale, but maybe a little from the install. Some long time dealers are getting turned in because they are not hvac licensed or bonded or both, so they are forced to stop doing installs also. It really makes me wonder what things are coming to when people will drive a few hundred miles to buy an OWB to save a few hundred bucks, knowing full well they won't get any dealer support. I'll bet nearly all the small dealers will be gone up here in 5 years or so and replaced by the large super centers. What do you think?
Marty
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Marty, the only thing I can tell you is that my market is like going back in time 20-30 years compared to
most. If a "home inspector" or anyone like that tries to tell someone here that he can't do something to his own home, the inspector better be listening for pump action of the ol shotgun, sounds crazy but it's true lol
up north it seems folks and business in general seem strangled by govt regs, here it's just not like that. It's extremely rural and like I said it's like going back in time, there was a special on dateline a couple years ago about this area, showed people out burning tires and sittin around chugging mt dew as fast as they could open it. There are areas around here where it's a lot more civilized in the central part of the state, but in the east it's still laid back.
My goals for fighting off the big push is to become a bigger dealer, I'm pushing my advertising budget way up and really getting my name out there to help ward off the scenario you mention. As this is my only income besides rebuilding a few vehicles a year.
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I applaud any and all of you dealers in today's market. I am guilty of buying online cheaper than local. My only excuse is there is no Wood Doctor dealer in Michigan to my knowledge. For you guys to front the $$$$$ for in stock stoves and the supplies then GIVE away your knowledge to boneheads like me to hook our own up because we watch HGTV and think we can do just as good as a professional, takes a lot of guts. Although my skills are higher than the general public, it just pays sometimes to call in the cat that does this for a living.
Gentlemen (and ladies too), My hat is off to you.
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I second this /\ /\