Water to Air HX in existing forced air handler

[dogwood]

Medman, the plenum piece with the cooling coil in it is 19.5" front to back, 20'' wide and 24 'high. it fits right over the top of the existing Lennox furnace leaving about 6" of the top front of the furnace not covered by the plenum and about a half inch on either side likewise. . The plenum piece above reduces the width to about 14" with the other dimensions remaining the same on it. I hope to get a heat exchanger fitted in right beneath the lower plenum piece with the cooling coil in it, and over the new modular blower unit. The unit which will max aout a 2100cfms, which is 100 cfm per each of my existing 21 heat vents. I will attach a picture on my next post. My new 4-5 ton rated blower from Alpine, http://www.alpinehomeair.com/viewcategory.cfm?categoryID=390, or the better variable speed model of the same, will be 24" wide x 21" front to back with a 23.5" x 11.25" supply air opening. Great tip on the clean out. None currently exists, but a big mess inside probably does. Thanks. Meanwhile I note Alpine's modular blower price increased to $602 for the multiple speed, $1080 for the variable speed, not to mention another $201 for the electric heating coil. and their prices are good.

 

[pybyr]

Trevor, I mostly grasp what you are saying but am unsure of what you mean by the furnaces "outlet bonnet". Are you describing the whole top surface of the furnace or just the 21x22 opening? On re-reading your post, what I am picturing is a 24x24 water to air hx sitting over the smaller 21x22 opening, with the hx having a flange sticking outwards, that sits on the flat top of, and is screwed or duct-taped to, the furnace top.

You got it

I already have the reducer plenum piece you describe in place over the existing plenum piece containing the existing cooling coil. Does this sound like what you have? I wish I had a side-view drawing (hint) of what you ordered from Ross at Nationwide Coils so I could better visualize what the part-inverted flanges look like so I could order the same. Are the outside edges of your hx exposed and functioning as the plenum enclosure for the width of the hx? Did I ask you enough questions? Thanks for your help. Maybe Nationwide Coils will have your order on file and adapt it for me size-wise. I've got 3000 sq. ft. home with 10 ft. ceilings to heat. Probably calls for a similar in size hx to what you've got.

I don't have any drawings/ diagrams, but you can find some photos here:

https://www.hearth.com/talk/threads/25090/

 

[dogwood]

Thanks Trevor and Medman. Trevor, the heat exchanger in the previous thread was impressive. I must and will have one. What size are the inlet and outlet pipes? Would you have done anything differently if you were reordering the hx now or have any further advice before I call Ross and order? Thanks again. Medman, pardon me if I don't post the pictures you requested tonight. I am exhausted. You both have been a big help with this aspect of our installation planning.

Mike

 

[pybyr]

Thanks Trevor and Medman. Trevor, the heat exchanger in the previous thread was impressive. I must and will have one. What size are the inlet and outlet pipes? Would you have done anything differently if you were reordering the hx now or have any further advice before I call Ross and order? Thanks again. Medman, pardon me if I don't post the pictures you requested tonight. I am exhausted. You both have been a big help with this aspect of our installation planning.

Mike

Glad to help- lots of folks on here have helped me and I like to try to do the same when I can.

Pipes of the "headers" and inlets/ outlets are 1.25 inch. I did that so that they'd be the same size as the pipes for the rest of my system (so as to meet the same standards of plenty of flow/ low pressure resistance/ no need for large circulators). Pipe of the layers within the coil is 1/2 inch. These are areas/ variables that stand out compared to the lower price units, which I think I recall have smaller diameters. The "case" of sheet metal around my coil is as large as it is (height above and below the actual tubes and fins) only because I needed to fill in that much space between the top of my furnace, and the bottom of the next duct fitting above the furnace, and since (at the time) there was no upcharge for such tall flanges, I decided to do it with the coil's own case instead of needing to fabricate even more metalwork than I was already into. Otherwise, no need for such a big box around the core of the heat exchanger- it could probably be only 6 inches or so. Be prepared for the fact that a unit like this will have some hefty weight, in terms of the rest of your layout/arrangement and working space, or getting help. Anything I'd do differently? Well, if I'd had more of a clean slate, I might have gone with something other than forced air entirely- but no regrets on how this coil is made and how it works.

 

[dogwood]

Trevor, Medman, what type circs are you using to supply the hot water to your w/a hx. Mine will be a dedicated circ to the w/a hx only. I am going to go with Pybyrs w/a hx, and Medmans wiring, fan, and T-stat arrangement that can vary the air supply side as called for. I was wondering whether the water circ pump should have some variable speed function as well, or would it be wiser to use a simpler single speed circ pump. You read about the ECM, Delta T, 3 speed, and probalbly other type circs in posts frequently. What did you go with and what would your advice be. How many BTU's are you pushing out of your hx; as many as you hoped for? Trevor, in the picture in the post you provided the link to, is the way the HX was sitting on the floor in your picture the direction you installed it on the furnace, or were we looking at the underside face up? Did you cover the side with the exposed inlet pipes with sheet metal to cut down on heat loss or leave it exposed as is? If the picture showed the hx topside down it looked like you allowed about a 5-6" inch space for the air to circulate from the blower underneath the actual hx elements. That looked like a sensible arrangement. Is that what I was seeing?

Wish me luck on getting my 1600 lb. boiler, being delivered today, at least into the garage. It ought to be quite a trick using only the rental truck's liftgate to lower it to the ground and a hand pulled 5000 lb. pallet jack to get it inside. I'm lowering my thousand gallon storage tank off its trailer too today. If there are no more questions or posts from me it means I've not survived the experience or been squashed altogether. Thanks again for sharing your experience and expertise.

Mike

 

[Medman]

Good luck with the offloading of the boiler. I remember the day I did that - final placement was achieved with an F150, a towstrap, and crossed fingers. We had to use the truck to swing the boiler around 90*.

As for circs, I new that my config. was temporary until I could install storage, so I just used a taco 007 for the hx loop. It worked well, I got the heat I needed out, and I figured a rough delta t at the hx of 23-24* water temp.

A variable speed circ in conjunction with an outdoor reset sensor may be a better option to heat most efficiently.

 

[pybyr]

Let us know how the move-in of boiler and tank went.

I'm using Wilo Star 3 speed circs- Patriot-Supply.com had some very good deals on them when I was buying, and the quality of design and construction are each superb. I was really tempted to go with ECM type circs (because of their advantages in lower power consumption), but they had not really yet hit the US market last year (at least in residential sizes) when I needed to make decisions and start ordering parts.

The delta-T or setpoint circs have distinct advantages (for some situations), that, again, I was intrigued with, but I needed to pick, order, and get moving, and figured that I can evolve things at some point, if need be, with outboard circ controls.

My system ran in a preliminary install mode without storage last January through the end of the heating season; I didn't yet do any insulation around the HX or elsewhere; I intend to, but have wanted to finalize some things first. I did not do a lot of fine-tuning of settings on the circs or measurement of BTUS, but with good wood and a good fire, the Econoburn 150 + my water-air HX would bring he house up in temperature more quickly than my 125,000 BTU/hr Thermo Pride oil unit- which =

As to the layout of the tubes and fins within the HX's body, if you orient the tubes and fins horizontally (which I have in its final install), then the empty space of the HX case's box is equal both above and below- as you mention, that gives good room for the air to spread out to the full width of the coil on the air inlet side, and then to get ready to neck down into the duct reducer on the outlet- with, I hope, good and relatively even airflow through all parts of the HX's fins and tubes.

PS, a scissor jack under one portion of a boiler/ tank, and a hand-powered come along, worked wonders to get my boiler to its exact location.

Trevor, Medman, what type circs are you using to supply the hot water to your w/a hx. Mine will be a dedicated circ to the w/a hx only. I am going to go with Pybyrs w/a hx, and Medmans wiring, fan, and T-stat arrangement that can vary the air supply side as called for. I was wondering whether the water circ pump should have some variable speed function as well, or would it be wiser to use a simpler single speed circ pump. You read about the ECM, Delta T, 3 speed, and probalbly other type circs in posts frequently. What did you go with and what would your advice be. How many BTU's are you pushing out of your hx; as many as you hoped for? Trevor, in the picture in the post you provided the link to, is the way the HX was sitting on the floor in your picture the direction you installed it on the furnace, or were we looking at the underside face up? Did you cover the side with the exposed inlet pipes with sheet metal to cut down on heat loss or leave it exposed as is? If the picture showed the hx topside down it looked like you allowed about a 5-6" inch space for the air to circulate from the blower underneath the actual hx elements. That looked like a sensible arrangement. Is that what I was seeing?

Wish me luck on getting my 1600 lb. boiler, being delivered today, at least into the garage. It ought to be quite a trick using only the rental truck's liftgate to lower it to the ground and a hand pulled 5000 lb. pallet jack to get it inside. I'm lowering my thousand gallon storage tank off its trailer too today. If there are no more questions or posts from me it means I've not survived the experience or been squashed altogether. Thanks again for sharing your experience and expertise.

Mike

 

[dogwood]

It was an all day sucker, but my wife and I finally got that behemoth Solo Innova 50 off the truck and into the garage using a come-along. a 5000 lb. pallet jack I lucked into off Craigslist last week, and good fortune. Our driveway slopes away from the garage, making the boiler want to run away into the back of the rental truck every time the pallet jack lifted it off the trucks floor. Its a lot of weight to control. The off-loading and moving of the 1000 gallon tank will have to wait until Saturday. I've been reading and studying all your posts for so long it seems almost unreal the boiler is physically sitting out in the garage. Medman and Trevor, appreciate both your latest replies and hope I can help you both out one day in return.

One other note; the people at BioHeat were very helpful, especially Delores, don't know her last name, who helped with a couple shipping snafus. On the other side if any of you out there orders from them, ask for a stronger, or reinforced, pallet to adequately bear the weight of the boiler and accompanying parts. The one sent was sagging under the boilers weight and needed some reinforcement before off-loading. Otherwise they, including their technicians, have been a pleasure to deal with. I would recommend them (and Chris Hoskins, who posts here sometimes) to anyone interested in a boiler purchase. Time to put my feet up.

Mike