Any HVAC folks here?

[Hogwildz]

Apologies if I am inserting this in wrong room.
I am looking for advice in running duct from my existing oil forced air furnace to my addition. Would be heating with wood in addition, but want the furnace for backup.
Going to zone main house & additiion. Main is in place, need to run addition duct and need help figuring sizing & stepdown in sizing.
Any help would be mucho appreciated. ELK? LOL
Even anything to point me to info would be great. Seams the HVAC forums are stuffy, and they don't care for none industry folks or do it yourselfers.

 

[BrotherBart]

The HVAC newsgroups and forums are snakepits.

 

[elkimmeg]

Hah Bb I love them they they don't really take to me, Someone outside the business knowing more code than they care to hear
most would like to go unregulated. I get in many more heated discussions there.They do not want to here Bubble wrap is only R1.1 and not the R4.2 stamped and that it fails the flame
spread test. should be banned

Hogwild I need to know the room sizing out side wall exposure glass area and insulation to advise coverage also just as important a return route and sizing then describe what space is available for routing. Getting re technecial I should know the cfms of your existing furnace and how many take offs and their sizing If it is a big room what about a zone damper to split up your system/ I need more info. All grills should be dampered so that when your wood stove is running they can be closed off. Are you also planning for AC? If on a zone damper than thermostat will control that zone so closing off registers may not be needed

Part of this is remodeling and working with an existing system If your system is maxed out already the a zone damper is required Another posibility is a mini split system just for that room again I have no idea the current demand or the room size

May be the wrong forum room but Many members might learn a thing or two

 

[Hogwildz]

Hah Bb I love them they they don't really take to me, Someone outside the business knowing more code than they care to hear
most would like to go unregulated. I get in many more heated discussions there.They do not want to here Bubble wrap is only R1.1 and not the R4.2 stamped and that it fails the flame
spread test. should be banned

Hogwild I need to know the room sizing out side wall exposure glass area and insulation to advise coverage also just as important a return route and sizing then describe what space is available for routing. Getting re technecial I should know the cfms of your existing furnace and how many take offs and their sizing If it is a big room what about a zone damper to split up your system/ I need more info. All grills should be dampered so that when your wood stove is running they can be closed off. Are you also planning for AC? If on a zone damper than thermostat will control that zone so closing off registers may not be needed

Part of this is remodeling and working with an existing system If your system is maxed out already the a zone damper is required Another posibility is a mini split system just for that room again I have no idea the current demand or the room size

May be the wrong forum room but Many members might learn a thing or two

I kew you were going to ask all those pertinant point, and fully understand the importance. Give me a couple days to gather the info.
When asking for outside wall exposure, windows etc? That would be for addition only, correct? Since the main is already established? Routing will be from far end of basement about 30' to corner, up through floor vertical along inside wall angled through wall and then up into unused attic space. then trunking across attic to far wall.
Its roughly from furnace to far addition wall about 95', which includes horizontal & vertical runs complete. the addition is 1-11' x 16' office with 1 6' slider & 1 entrance door, with opening into entranceway which is roughly 7' x 8' with 1 french door.Entr. also has a doorway (existing entr. door) that will keep door thewre, but be left open at completetion. The office has another doorway into a walkthrough closet type room, 8'x8' which in turn has doorway into bedroom. The another (3 total) doorway into existing house again this time into a bathroom I will be constructing. That already has duct to that area. The bedroom is 25' x 15' with 3-6' sliders. block wall on one side, preformed concrete wall on other( garage). Last wall is against office wall. BTW office one end is to erntanceway, other garage.
I know this is a mess in typoe. I will draw up some diagrams & get measnurements for you. I could not see cfm's on the furnace label. Would it be on the fan itself? Which is on bottom and not sure how to get to it easily. I def want to 2 zone, 1 main, 1 addition. I figuers 1 controller, 2 dampers, 2 thermostats, and at least a bypass damper on the addition run. Yes I am hoping to run central A/C next summer. I checked into the mini splits, and don't feel they are enough for both the main & addition. Would rather run one unit with 2 zones. Seems more cost effective. I'll get you better info. Wouyld it be easier to email you the info once gathered.
I am leaning towards ductboard, its what the main trunk is, in basement. What is your opinion on ductboard?
I'm going to send you a PM. Thanks Elk. Very, Very uch appreciated!

 

[Hogwildz]

I sent you a PM Elk, Not sure if yours is still full or not, and fully realize your in high demand.

 

[elkimmeg]

95' run? even zoning it may not help in a 750 sq ft area one would use 4/5 6" duct feeds posibly one more is closets or other rooms separate that space

What about this idea, instead of a zone damper and running long trunk lines what about a second furnace or exchanger located within your addition area?
It could be sized correctly and effectively be a separate zone with short productive runs.

It may be possible to take hot water from your hot water heater and feed an exchanger, this would eliminate a need for a furnace make up air and exhausting it

You might only need 45,000 to 65,000 BTus to do what you need to do. I can do a heat takeoff once I know the other details such as glass area insulation ect

Did I hear you correct 10' ceilings? Having heating feeds in a ceiling that high will not be effective My suggestion is to feed and return that room high and low.
The best compromise solution for heating and AC.

 

[laynes69]

We have a large old 2 story home with 10' ceilings. I had the local hvac people do a couple of estimates to figure out how to heat the upstairs of this house. We had 2 supplies that were 4x12 that shared 2 rooms each, which totaled about 400 sq feet for each duct. So I decided to run the main heat trunk through the basement up the bathroom (First Floor) closet into the second story, into the attic and I branched the supplys off the attic into the ceilings of the upstairs. I then converted all of the old heat supplys into returns because they were all on the inner walls. The ductwork works good in the ceiling, if you have a good return on the floor, and to maximize the heat, you would need a ceiling fan. We keep the whole house about the same temp with the ductwork I installed. I used one 8" duct for a room size of about 250 sq feet and a 6" duct for the rooms around 170 square feet upstairs. Our only other option was 2 furnaces and that wasn't an option for me. It can be done, but plan it out wisely. I didn't step down our ductwork either on the main and the system works fine. I spent 1200 dollars on the ductwork last year, took me 3 months to do it myself. The estimates were 3200 to 3800 dollars.

 

[Hogwildz]

95' run? even zoning it may not help in a 750 sq ft area one would use 4/5 6" duct feeds posibly one more is closets or other rooms separate that space
Ok measured today, the total run from furnace across basement & over to corner to run up at:34'. Up through floor through wall into addition and up into addition attic 13'. Across attic to opposite side 25'. For an approx total of 72'

What about this idea, instead of a zone damper and running long trunk lines what about a second furnace or exchanger located within your addition area?
It could be sized correctly and effectively be a separate zone with short productive runs.
I am trying to do this for around $3,500.00 or less. Not sure thats an option with a second furnace & fuel tank & fuel. Was looking at LP furnace for that idea before. You seen the quote. Plus I want to add central A/C next year. still need the duct or then I am buying a big A/C unit for main & another maybe split for addition. Again Cost.

It may be possible to take hot water from your hot water heater and feed an exchanger, this would eliminate a need for a furnace make up air and exhausting it
No duct for A/C then, hot water heater with 4 person home, barely enough hot water as is. Have a 50gal which is just barely enough as is.

You might only need 45,000 to 65,000 BTU to do what you need to do. I can do a heat takeoff once I know the other details such as glass area insulation ect
I am sure 45-50k would be sufficient. Walls are 6" will be insulated, ceiling will have blown insulation somewheres between approx 20" deep.

Did I hear you correct 10' ceilings? Having heating feeds in a ceiling that high will not be effective My suggestion is to feed and return that room high and low.
The best compromise solution for heating and AC.

Yes just under 9'8", supply will be at bottom of walls dropping duct down from attic into bottom of each end of a large closet that is in between the office & bedroom. Returns will be through ceiling to better circulate air.
I am still working on better diagrams, & will measure glass etc. along with the diagram. Attaching diagram of existing setup in basement. Diagram is quick done so primitive. My apologies.

ok one fix: the second return duct marked from left, is not a return but is a supply. And the two all the way far left along the wall are also supplies to the two bedrooms on second story of main house. Fubar'd while rushing.

 

[Hogwildz]

We have a large old 2 story home with 10' ceilings. I had the local hvac people do a couple of estimates to figure out how to heat the upstairs of this house. We had 2 supplies that were 4x12 that shared 2 rooms each, which totaled about 400 sq feet for each duct. So I decided to run the main heat trunk through the basement up the bathroom (First Floor) closet into the second story, into the attic and I branched the supplys off the attic into the ceilings of the upstairs. I then converted all of the old heat supplys into returns because they were all on the inner walls. The ductwork works good in the ceiling, if you have a good return on the floor, and to maximize the heat, you would need a ceiling fan. We keep the whole house about the same temp with the ductwork I installed. I used one 8" duct for a room size of about 250 sq feet and a 6" duct for the rooms around 170 square feet upstairs. Our only other option was 2 furnaces and that wasn't an option for me. It can be done, but plan it out wisely. I didn't step down our ductwork either on the main and the system works fine. I spent 1200 dollars on the ductwork last year, took me 3 months to do it myself. The estimates were 3200 to 3800 dollars.

what size did you make your trunk, and approx how long was it from furnace to end in attic?

 

[laynes69]

You dont want ducts running directly off of the end of the supply. You need to have some pressure for the air to feed through the ductwork. What size is your current furnace? You want to go 72' to heat the addition right? Or how far would you need to go to heat this area?

 

[laynes69]

I ran close to 50 feet of supply trunk from the basement to attic, because my furnace isn't centrally located. I have a 8 x 18 trunk that feeds 5- 6" supplys and 3- 8" supplys. No stepdown in the trunk, I wanted the trunk open so the heat could be pushed up the home. The trunk runs up the center of the house, so its in a conditioned space. We don't have a problem with this setup, and hopefully down the road when a/c is installed it should cool okay. Its alot easier to move the heat where you need it, than to move cold air. I had to figure in the room size to how many supplys I would need. A couple rooms fall a little short on the cfm requirements, but heat just fine with returns. Its important to run your supply lines on the outer walls and the returns on the inner walls of the home. Also you will find you will lose some airflow in the flex duct because of the rough walls of the ducts.

 

[Hogwildz]

You dont want ducts running directly off of the end of the supply. You need to have some pressure for the air to feed through the ductwork.
Yes I know, this is how the house came when bought. I have to put the supply end duct up top just away from the end.
I just saw today that the returns are made out of the floor joists in the basement & where they run to the top of the return trunk its just a rectagular hole cut into the top of the return trunk, not sealed to the soffit metal they made the return branches out of. So basically alot of the return air is being sucked into these huge openings and suckng basement air in. I will fix this also after dealing with new duct. For the time being,m the existing system is working, and not too badly either.

What size is your current furnace? You want to go 72' to heat the addition right? Or how far would you need to go to heat this area?

Ok, want to run another supply & return trunk from furnace to addition = appros. 72 feet or so. add another close to 9' to come from addition attic back into closet and down to floor for supply. Now the return I can set up to be shorter, about 55' and they will be in the ceiling.
Furnace is 85,000-97,000 BTU's. Right now set for 85,000 BTU's with the .65 GPM nozzle. I can get the .75 GPH nozzle to get it up to 97,000 BTU's.
One problem is I do not know the CFM of the fan, It is not marked anywhere, I have minimal literature, not stating the fan CFM anywhere. And the fan is on bottom and I see no tag etc to get the CFM off of. I might have to pull the furnace apart to gete to the fan and see what I can find. I may try and calling the manufacturer and seeing what they can tell me. This furnace is a 2004 model, but I looked up on manuf. site and dont see it. Might be upgraded or dicsontinued already. Its an Armstrong Air 80.
Being so new I'd rather not have to replace it. I still think with what it has I should be able to work with.

 

[laynes69]

I will say, more than likely with that kind of run you will not be able to heat the addition off of the ducts currently. When you add square footage, you need more heat. You need more heat, you need more ductwork. Its kinda hard to follow not seeing your setup, and with a furnace that size, I don't think its possible. Our furnace is 120,000 btus which is a little overkill, but I think we draw close to 1200 cfms through it, maybe more. You could probably get away with a small electric furnace or even baseboard heat in the addition. If you wanted to go 2 zones, maybe then consider electric. I really don't think you can tie this addition of 750 sq feet into your current ductwork. You'll be looking into some costs.

 

[Hogwildz]

I will say, more than likely with that kind of run you will not be able to heat the addition off of the ducts currently. When you add square footage, you need more heat. You need more heat, you need more ductwork. Its kinda hard to follow not seeing your setup, and with a furnace that size, I don't think its possible. Our furnace is 120,000 btus which is a little overkill, but I think we draw close to 1200 cfms through it, maybe more. You could probably get away with a small electric furnace or even baseboard heat in the addition. If you wanted to go 2 zones, maybe then consider electric. I really don't think you can tie this addition of 750 sq feet into your current ductwork. You'll be looking into some costs.

I don't want to run the existing ductwork to heat the adddition, I want to run separate supply & return trunks direct from the furnace. And add zones. 1 for the main, 1 for the addition. Realistically, they wouldn't be running much at the same time. I would be making 2 zones, possibley a third for the main 2nd story at a later date. But for not two sets of supply & return trunks with their accompanied branches. Both off a control panel with separate dampers, thermostats & at the very least a bypass damper between the addition's supply & return trunks, being it is only 750 sf, I will def need it. I should beging install on the new insert this weekend. once thats finished and ductwork & zones finished. I will finish the addition. When I get the funds saved I will install a freestanding stove in the office in addition. The oil heat will just be backup is the plan anyways. But, I def need some central A/C, which none of the house has at this time. Hence the want to add the ducting & zoning to the addition. I do not have the cash for 2 separate heating & cooling systems. If I can get the new duct run & zone the main & addition to separate them. Then I can get the back up heat & A/C to the addition, as well as get some A/C to the main. House is very well insulated, very good windows etc. My old place I could feel the wind blow from front of house to back of house LOL.

 

[laynes69]

Maybe it could be done, but when both of those areas require heat, neither may be able to keep up and therefore the furnace would run continually. I'm not sure what to tell you, its going to be a difficult task and not going to be cheap. I would have all of my options considered, and If someone came out and discussed adding more ductwork, talk it through and install the ductwork yourself. But sounds to me like it won't work. Only so much can be done with one thing.

 

[Hogwildz]

Maybe it could be done, but when both of those areas require heat, neither may be able to keep up and therefore the furnace would run continually. I'm not sure what to tell you, its going to be a difficult task and not going to be cheap. I would have all of my options considered, and If someone came out and discussed adding more ductwork, talk it through and install the ductwork yourself. But sounds to me like it won't work. Only so much can be done with one thing.

I had the HVAC guy out to repair the furnace after the flood last summer. My grandfather was friends with his, my parents used his dad & him as their HVAC guy.
I trust his quality of work, but his price was too high. He had no problem running the 2 zones, but did say new trunks should be run for the addition zone. He also pointed out that supply branch on the end of the trunk, I need to do this myself to save funds. Running low and still need other things to finish addition. Plus I want to learn a lil about an aspect of construction I haven't done. I like the challenge & learning part.

 

[elkimmeg]

just like any zone be it FHW or FHA the first demand is met before it continues to thfulfill the second zone demand

Yes it could work is it the best solution no but we all make compromises when we have limited funds.

as for heat ceiling returns are useless good of AC

Ok a cheap way to get it done without breaking the bank Note its an improvement but not the best way it can n be done

Retuns instead of the ceiling location use a stud bay. cut what you need out of the top plate to fit 4/12 rectamgle boot to 6" round then within reaching distance high cut the sheet rock
and install a dampered grill futher down the stud cavity about a foot off the floor install another dampered grill. Choose an inside wall with separation to any feeds. Now do the same in another location where you have atleast two setups as I descibed
During winter heating you will close off the top vented louvers for AC open the top and close the bottom total additional cost $25 balancing and even effecient flow of heat priceless

PM me your phone ##

 

[Hogwildz]

just like any zone be it FHW or FHA the first demand is met before it continues to thfulfill the second zone demand

Yes it could work is it the best solution no but we all make compromises when we have limited funds.

as for heat ceiling returns are useless good of AC

Ok a cheap way to get it done without breaking the bank Note its an improvement but not the best way it can n be done

Retuns instead of the ceiling location use a stud bay. cut what you need out of the top plate to fit 4/12 rectamgle boot to 6" round then within reaching distance high cut the sheet rock
and install a dampered grill futher down the stud cavity about a foot off the floor install another dampered grill. Choose an inside wall with separation to any feeds. Now do the same in another location where you have atleast two setups as I descibed
During winter heating you will close off the top vented louvers for AC open the top and close the bottom total additional cost $25 balancing and even effecient flow of heat priceless

PM me your phone ##

I thought using wall cavity for returns was abolished? Not that I am complaining, It will make it much easier.

 

[elkimmeg]

I have mentioned this solution before for all those people that have upstairs ceiling returns the entire setup is so ineffecient
Firts of all stud bays are not allowed in comercial construction but allowed in residential codes remember I did not say this is the best way.
Better would be running a rectangle or oval piece in that bay cavity and make your cut outs.
m,However locating the reterns as I suggtested vastly improves your effeviency and over all circulation.
By having a low return you are removing the cold air at the floor level as you remove that cold air you are drawing the heat down
warmer air will replace the colder air.

There is even a way to make the stud bay more effecient. One could line the studs with 1/4" self stick weather stripping befor the sheetrock is applied and caulk and seal the entire bay
The second way is to caulk everything inside the bay and apply a bead of caulk on the face bothsides of the studs prior to sheetrocking. Again this would form a gasket type seal.
Sealing the bays prevents air leakage and promotes a betted draw from where you want to draw

The solution is so simple and cost so little but the improvement is astounding you are now returning the air in a location it was meant to be returned Returning the warmest ceiling air
is assinine This helps account dor 35% heat loss in transmission of all attic location furnaces or exchangers
Unfortunately code says supply = returns, but There is no language requiring detter design or locations

In my town I have influenced the way things are done many HVAC contractor got tired of explaining and admitting that this is a better application to their builders.
It is now common to see hight and low returns in many of our new homes. Call it a little arm twisting but it save fuel usage and we all pay the price of that
What really changed the change over was ,one realator pointing out the mertit where one builder employed high low returns. Pretty soon other builders followed siut.

When the discussions come around again joe home owner with agerage skills can convert and relocate returns in wall cavities as I suggested any weekend.

As I sauid many times auxhilary heat insert your stove prefference______ is one part of the solution making your home energy effecient is the other part

 

[Hogwildz]

I have mentioned this solution before for all those people that have upstairs ceiling returns the entire setup is so ineffecient
Firts of all stud bays are not allowed in comercial construction but allowed in residential codes remember I did not say this is the best way.
Better would be running a rectangle or oval piece in that bay cavity and make your cut outs.
m,However locating the reterns as I suggtested vastly improves your effeviency and over all circulation.
By having a low return you are removing the cold air at the floor level as you remove that cold air you are drawing the heat down
warmer air will replace the colder air.

There is even a way to make the stud bay more effecient. One could line the studs with 1/4" self stick weather stripping befor the sheetrock is applied and caulk and seal the entire bay
The second way is to caulk everything inside the bay and apply a bead of caulk on the face bothsides of the studs prior to sheetrocking. Again this would form a gasket type seal.
Sealing the bays prevents air leakage and promotes a betted draw from where you want to draw

The solution is so simple and cost so little but the improvement is astounding you are now returning the air in a location it was meant to be returned Returning the warmest ceiling air
is assinine This helps account dor 35% heat loss in transmission of all attic location furnaces or exchangers
Unfortunately code says supply = returns, but There is no language requiring detter design or locations

In my town I have influenced the way things are done many HVAC contractor got tired of explaining and admitting that this is a better application to their builders.
It is now common to see hight and low returns in many of our new homes. Call it a little arm twisting but it save fuel usage and we all pay the price of that
What really changed the change over was ,one realator pointing out the mertit where one builder employed high low returns. Pretty soon other builders followed siut.

When the discussions come around again joe home owner with agerage skills can convert and relocate returns in wall cavities as I suggested any weekend.

As I sauid many times auxhilary heat insert your stove prefference______ is one part of the solution making your home energy effecient is the other part

Sounds like a winner to me. I am using 8" tongue & groove pine for the walls all around. I guess I have 2 options, line the cavity with sheet metal and cut the high & lows as you described, or weather strip the 4 corners of the bay & seal each joint in the tongue & groove where it covers the bay? Or is wood a nono in making a bay duct?
I know, I know would be simpler with sheetrock, but I am using the 8" tongue and groove. Completed the ceiling with it and looks great! I am no fan of sheetrock, worked on much to much of it for my taste.
When you get a chance gimme a buzz. I'm here all day today, on road tomorrow till the afternoon, andhere all weekend installing the Summit finally.