Boiler to Forced air plumbing help/suggestions needed

Be careful with the coil measurements as they are usually of the finned area. You need the actual outside dimensions, scroll down to the data.
http://cgi.ebay.com/18x18-Forced-Air-Pl ... dZViewItem
This one looks like it fits your dimensions and is three 3/8" tubes w/1" sweat connections.
It looks wide enough.
http://cgi.ebay.com/18x18-Forced-Air-Pl ... otohosting

The outlet on your EFM 520 is 3", the return is 2" but don't worry about that. Remember these boilers are built and rated for steam too. That is the reason for the big ports.

Yanche's point about the coil is correct for standard heating coils. The outdoor furnace/cordwood eaters are ineffiecient, their transfer of heat is not. The exchangers made for these applications are not standard 2 row design, but three rows. In addition the fins are wider spaced to reduce what impact it has on the open plenum blowers that they are installed with. They spent a ton to get this stuff right and they did, it works well. It's only their heatsource that is different (yes, they picked the wrong one). There is a lot of engineering data at these ODF places have on their websites to support exactly what you are doing, so use it to your advantage. Look at their installation manuals, charts and drawings it will show you step by step what you need for a pump/controls/saftey/and heating end.

The run from the boiler to the coil is only about 6', actually there is a total of only about 15' of pipe connecting the boiler to the coil (well, where it will be). I think the Taco 007 will do the job and I'm going to try it because it came with the boiler but I actually think it will probably circulate without a pump because the inlet to the coil will be about 6" lower than the top of the boiler so it should flow naturally. I know from an engineering standpoint there is an ideal way to do things, from a penny-pinching standpoint there are alternative ways that will work. Back in the bad old days we had a wood stove in the living room. 95 degrees in the living room to keep the spiders warm and 50 degrees everywhere else In any event I'm way ahead of my coal budget where it looks like I might break even or even save money this year vs. 5 or more years if I had a plumbing contractor come in and do everything. That includes all the equipment and fuel costs and the cost of coal vs. just using propane. I'll be sure to let you guys know how it works (or doesn't work ) when it's cold out. I have a need for the ashes also so they will come in handy paving a path to my chicken coop.

A Taco 007 will be more than enough of a pump. I use 007's just about everywhere. I push water as far away a 150'. As long as you aren't pushing the water a long way uphill they work fine. And you can't beat the price.

If the coil will gravity-flow, you will have a really good setup, a slightly warm coil most of the time, with thermostaticly controled added hot water to the coil when called for. With a constant running blower fan, you should have very even heat.

Greg L

LsFarm wrote:A Taco 007 will be more than enough of a pump. I use 007's just about everywhere.

According to the spec sheet for the Taco 007 it will pump10 gallons per minute at 8' of head.

You need an air scoop and air bladder pressure tank in the loop to the heat exchanger, you will not need a bypass. This will keep air out of the system. It should be mounted at the highest point in the loop, best if it is the line from the top of the boiler to the exchanger. A 12# PRV at your water supply is required to maintain the proper pressure in the boiler. If your coil's temp in and out is no more than a 20* drop the TACO is fine. I have one and it does a good job with 3, 3/4" zones off a 1" feed.

It is set up right now with a 1-1/4" flow-check off the center top outlet, that flows horizontally to an air scoop with a #30 expansion tank screwed to the bottom port and a watts air valve screwed to the top port (just like the instruction manual diagram). From there I have it adapted to 1" to the top of the duct coil. The bottom of the coil is 1" which then connects via steel pipe to the Taco pump which is next to the boiler. The other inlet on the boiler has a drain valve and a 12# B&G pressure regulator/fill valve and where it connects to the house there is a shut-off. I will more than likely install 1-1/4" gate valves on both the inlet and outlet boiler ports so I can replace parts in the future without draining the boiler. There is a 3/4" bypass pipe that goes from the top port to the bottom port on the boiler, the guy had it set up that way. The instruction manual says use 1-1/4" bypass and connect both inlet ports but I really don't understand why that is needed, once I get more info from EFM I'll change it if need be.

If you don't connect both inlet ports you may have stagnate water on the side of the firebox that has the inlet plugged. Both sides of the upside-down 'U' that makes up the firebox need to have inlet-water coming in. Otherwise there is nothing making the water circulate.

Greg L

LsFarm wrote:If you don't connect both inlet ports you may have stagnate water on the side of the firebox that has the inlet plugged. Both sides of the upside-down 'U' that makes up the firebox need to have inlet-water coming in.

That will also reduce your efficiency, long term it could degrade the steel in the wall of the water jacket. If a lot of material settles into that side and displaces the water from the steel, wall temperatures could rise enough and over time crystalize the steel. Rolled steels have a grain similar to wood. When exposed to repeated overheatings it will crystalize and have the structure similar to a sugar cube. That would not be good. A good install has the feed coming up to a Tee with a cap on each side. You can then clean the sediment by removing the pipe caps and rodding the belly of the boiler out with a wire brush or such. Depending on your water, I would go no more than 5-10 years without inspection and cleaning.

e.alleg wrote:It is set up right now with a 1-1/4" flow-check off the center top outlet, that flows horizontally to an air scoop with a #30 expansion tank screwed to the bottom port and a watts air valve screwed to the top port (just like the instruction manual diagram). From there I have it adapted to 1" to the top of the duct coil. The bottom of the coil is 1" which then connects via steel pipe to the Taco pump which is next to the boiler. The other inlet on the boiler has a drain valve and a 12# B&G pressure regulator/fill valve and where it connects to the house there is a shut-off. I will more than likely install 1-1/4" gate valves on both the inlet and outlet boiler ports so I can replace parts in the future without draining the boiler. There is a 3/4" bypass pipe that goes from the top port to the bottom port on the boiler, the guy had it set up that way. The instruction manual says use 1-1/4" bypass and connect both inlet ports but I really don't understand why that is needed, once I get more info from EFM I'll change it if need be.

Current recommendations are for the circulating pump to be installed on the supply side of the heating loop to push water in the circuit--not pull as I understand your installation.

[/qoute]Current recommendations are for the circulating pump to be installed on the supply side of the heating loop to push water in the circuit--not pull as I understand your installation.[/quote]

Yanche or Greg (maybe someone else) pointed that out some time ago. That may be fine for gas/oil installs but I have always felt that the overshooting temperatures that you see with solid fuel devices negate that thought for me. I would mount it just prior to the boilers twin feed legs. About a foot or so from where they split will give you a cooler running pump. It will pump no matter where you put it as long as there is no air, how long it lives is another matter.

I prefer pushing water through the heat exchanger/boiler. The reason is that if there are hot spots that create a few bubbles of steam, these won't be drawn through the pump causing noise and cavitation. The very slight pressure increase in the system after the pump will also help keep the hot spots from boiling the water.

Ford flathead engines in the 30's and 40's [and maybe later] had twin waterpumps, one mounted on each the cylinder heads and pulled coolant through the engine block and heads. This proved to be a real problem as the localized hot spots created bubbles and the pumps stopped pumping because they can pump liquids, not vapor. All modern engines push water through the engine for this reason.

I'm not sure of the reason bdhind the current convention of putting the pump on the output side of the boiler, my slightly paranoid thought process makes me think the companies will sell more pumps this way.

Either way the pumps are part of a continous loop of moving liquid, so the pump will circulate the water regardless of where it is placed.

Greg L

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Bob wrote:Current recommendations are for the circulating pump to be installed on the supply side of the heating loop to push water in the circuit--not pull as I understand your installation.

The reason you put the pump on the supply side of a boiler is to assist in getting the air and other dissolved gases out of the water. The inlet side of the pump will be the lowest pressure point in your circulation loop. The supply side of your boiler is also the hottest point in the system. Heat will liberate the dissolved gases. The two effects, low pressure and hot temperatures work together to remove the gases, mostly air and dissolved gases containing oxygen. You don't want the corrosive effects of oxidizing gases in your boiler water. You need an air scoop on the output side of the pump. Correct plumbing is ... boiler supply outlet to a two foot horizontal pipe to the air scoop inlet, then pump inlet. The horizontal pipe encourages the gases to flow to the top of the pipe where they can then be removed by the air scoop.

Edited to correct "Correct plumbing .... " I must have been asleep when I first wrote it

I strive to make my boiler piping systems closed loop and sealed. I look at it like a refrigerant system, have the right fluid in the correct amount and then leave it alone. To my way of thinking makeup water feed is a band-aid. You have a leak and you should find and fix it. Good water is water that has the trapped gases removed and a neutral PH. I add a base solution to my acid well water until I measure a neutral PH. Once the gases are removed by the air vent I screw down the metal tire valve type cap on the air vent to seal the system. I find when a system cools it creates a partial vacuum and will pull air in through all weak seals. I find the stem seals on ball valves to be especially troublesome. They seal under pressure but not under vacuum. I have large 270 degree movement pressure gages at the lowest point (boiler level) and highest point of my piping. I can easily see the pressure change as the boiler water temperature changes and/or identify a leak.

You are absolutely right Yanche. But at 150-160 degrees the water has already lost its air for the most part and will not entrain it even in a vented feed tank. The only new air will be in tiny amounts when the PRV adds a tad of water to the system to maintain pressure. I feel this is easily exceptable. I do not want my pump seeing the high temps that I get from my boiler's output, as it has gone 240* and more a few times. To me, the pump life is more important than the bubbles.
This is why I stated the gas/oil vs. solid fuel earlier. The gas/oil will always shut down at the limit setting, while the solid fuel will overshoot it's limits at times and that beats up the pump.
By the way, the pumps temp limit is 240*, that doesn't mean I want it to operate at it.

http://www.pexsupply.com/product_dtl.as ... co&cID=289


Greg may be on to something with the new spec ($$$$$$$$$$$).