Add a water to air exchanger in forced Air unit

Hi Gents,
I'm pondering the idea of adding a w2a exchanger to existing forced hot air unit as my dump zone for my DHW coil. Last year i dumped anywhre from 10 to 30 gallons of water a night, Thats alot of wasted energy. Can I use a thermoshiphon with this or use a aquastat with a slow circulating pump? If the coil is cold due to the use of DHW will it have the opposite effect in coolong down the air going thru it. Sounds like a good idea but not sure of it. I also dont have the space for a temering tank, I could install a section of baseboard heat but it already 80 in my basement when stove is cranking. Any suggestions?

Bpashocker wrote:Hi Gents,
I'm pondering the idea of adding a w2a exchanger to existing forced hot air unit as my dump zone for my DHW coil. Last year i dumped anywhre from 10 to 30 gallons of water a night, Thats alot of wasted energy. Can I use a thermoshiphon with this or use a aquastat with a slow circulating pump? If the coil is cold due to the use of DHW will it have the opposite effect in coolong down the air going thru it. Sounds like a good idea but not sure of it. I also dont have the space for a temering tank, I could install a section of baseboard heat but it already 80 in my basement when stove is cranking. Any suggestions?

Can you put the baseboard on the main floor of the house ?

Do you take your dhw right off the coil ? You say you don't have room for a tempering tank, seems that would be the best way to go, do you currently have some other hot water heater you could tap into ? If you add some type of heat exchanger to bleed off excess heat, if your dhw runs through it, you may not have enough hot when you need it.

I could put a baseboard on main floor, it would take some a lot of plumbing mods and would probably look out of place since the rest of the house forcrd hot air.
I have a oil fired hot water tank made by Bock with a quartz liner that the DHW coil is tied into to draw the hot water from. It only holds about 29 gallons and because the oil fired hot water tank heats up so fast it doesnt need a lot of capacity gallons wise. If i was to use hot water every 6 to 8 hours i would have no problem. My wife was also starting to complain about the temp drop off after the second shower. So I need a way to keep the hot water tank on and not dump 10 to 30 gallons a night depending on if the stove is cranking or just idle. I'll take pics to take any suggestions on making my whole unit more effecient.

Here is some pictures,sorry I tried to rotate picture but is was a pain in the a$$

Wow, at coal college you learn, learn, learn. I decided that I would keep DHW on propane as there is just the wife and I now. They want to charge me $5.50 a gallon and tank rental and I am really getting mad so I am looking at this afresh. I think an internal coil on my Pocono would also generate way to much HW and I have similar problems of dumping that heat. So how about this:

http://cgi.ebay.com/Hotwater-Wood-Coal- ... 19bfd3a64e

Could I move it, block it, empty it and generally have more options. I hear complaints about summer rusting etc. with those internal coils.

Bpashocker wrote:Hi Gents,
I'm pondering the idea of adding a w2a exchanger to existing forced hot air unit as my dump zone for my DHW coil.?

Since your already heating the plenum with the coal fired air scorcher - that hot space will not provide a graceful dump - Second if you had a HX in air handler - the only way it will exchange is if you have air moment so you will either create a short simply make air moment between the two stoves - or you will also pick up hot air from the coal appliance and sent it all out to the house - causing it to heat up past set point

Drafty - hot eccch forced air.......

you may be better served by diverting excess energy from the DHW storage to a length of fin tube with a zone valve - that zone valve could even control a simple box fan to blow the energy away from the fin tube. The heat energy would be lost into the basement - but all that uninsulated basement block will act as storage too/ or at least stay warm and not suck the basement cold as easily.

Kind Regards
Sting

How about adding a circulator pump . It will move the water more quickly and mix it better with the tank . It will pick up a lot more heat with normal convection and won't always mix as well in the storage tank . That will probably help a lot and you will need one anyway if adding a dump zone ,so try the pump first . You are not drinking it so all you need is a standard pump ,no bronze or ss . Dave

coalnewbie wrote:Wow, at coal college you learn, learn, learn. I decided that I would keep DHW on propane as there is just the wife and I now. They want to charge me $5.50 a gallon and tank rental and I am really getting mad so I am looking at this afresh. I think an internal coil on my Pocono would also generate way to much HW and I have similar problems of dumping that heat. So how about this:

http://cgi.ebay.com/Hotwater-Wood-Coal- ... 19bfd3a64e

Could I move it, block it, empty it and generally have more options. I hear complaints about summer rusting etc. with those internal coils.

I have only had my Hilkicoil for two seasons, but so far no rust on the SS. If you take good care of it and get a decent quality SS it should last quite some time. I guess you could use that hotwater add on but it's quite costly for some tubes in a case. You could probably make the same for half the price.

Sting wrote:

Bpashocker wrote:Hi Gents,
I'm pondering the idea of adding a w2a exchanger to existing forced hot air unit as my dump zone for my DHW coil.?

Since your already heating the plenum with the coal fired air scorcher - that hot space will not provide a graceful dump - Second if you had a HX in air handler - the only way it will exchange is if you have air moment so you will either create a short simply make air moment between the two stoves - or you will also pick up hot air from the coal appliance and sent it all out to the house - causing it to heat up past set point

Drafty - hot eccch forced air.......

you may be better served by diverting excess energy from the DHW storage to a length of fin tube with a zone valve - that zone valve could even control a simple box fan to blow the energy away from the fin tube. The heat energy would be lost into the basement - but all that uninsulated basement block will act as storage too/ or at least stay warm and not suck the basement cold as easily.

Kind Regards
Sting

The problem is its not a air scorcher. It take quite some time to heat up the house and keep it heatted. I keep the temp around 68 and use about 1.2 tons of coal a month. The house was built in the 90's with decent insulation. I have to turn blower fans way down to 20% to get any decent heat from the vents. I know there is a lot that goes into heat loss calculations and i know the design of the forced hot air unit is not the best all thought when the furnace is on the house heats up quite fine. Just trying to find a way to add some more btu's to heat the house. Maybe i need to rething the way the system is plumbed into the cold air return. I noticed most people plumb there intake blowers into the Cold Air return also. I may have to re think some things. Thanks for the advice

Flyer5 wrote:How about adding a circulator pump . It will move the water more quickly and mix it better with the tank . It will pick up a lot more heat with normal convection and won't always mix as well in the storage tank . That will probably help a lot and you will need one anyway if adding a dump zone ,so try the pump first . You are not drinking it so all you need is a standard pump ,no bronze or ss . Dave

Not a bad idea, but if i ad a circ pump i should just add a dump zone also. Maybe i need to duct in my intake blower on the back of my Hyfire II like everyone else. Not sure if it would help?

The coil must be on the supply side of the air handler fan

If its in the return plenum - the safety switches in the air handler of a traditional furnace will sense a problem -- and shut down - or that expensive fan motor will burn out.

manual or automatic dampers must also be incorporated in the forced air supply trunks if you have multiple hot air sources.

if the stove is undersized for the load to begin with -- there is no silver bullet to get more energy out of it.