Heat and Air Duct Advise

[Sigarms]

What does a load calculation involve? This is just a 800sf building, can it really be this difficult?
Help
DAve

Basically... location, R-value of structure and Windows. Figure out the cooling/heating for each area and plan ductwork for the load. Don't forget if you're doing a church, plan for maximum occupancy LOL Usually no big deal (load) however, you can take the same size structure and play with the variables and you'd be surprised on the difference.

 

[kenmac]

here you go


Mr. HVAC Free Heat Gain and Loss Calculator

 

[fuseboxer]

Do not forget to balance your system properly with the correct return air duct return air.

 

[bruceha2000]

Do not forget to balance your system properly with the correct return air duct return air.

That is also what I was thinking when I saw the schematic. The HVAC guys can respond better but I think you need a return in each room, unless you never close the doors. Near as I can tell there is only one return at the far end of the house in the kitchen. I think you are going to get a wicked cold breeze running back toward the kitchen when it fires up.

My current house came with a gravity feed furnace that apparently was originally coal but converted to oil (burner in the clean out door):confused2:
The house was basically 2 floors 15x24 with the kitchen tacked on the back, 30" door (thus 32') and the bathroom stuck on the side. Staircase went up 5 steps along the south wall to a landing then turned 90 to go north to the 2nd floor. One room on either side of the 'exit'. There was a second set of 5 steps along the south wall going to the landing from the living room that had been removed. I can't for the life of me figure out why in a house that small. Anyway, the 4'x4' grate was between the living room and dining room, the N/S part of the stairs was IN the living room and I had a couch against the south wall where the second set of steps had been removed. I can tell you it was SOME kind of cold breeze sitting there when the furnace came on, especially in the morning when the thermostat had been set low for the night.

 

[Sigarms]

Dual zone ductless mini split.

 

[OKnewguy]

Well I performed the head load calc (thanks for the link!) and came up with 42,830 heat loss for heating and 11451 btu gain for cooling.
Now to give you an idea of what the current 2 bids both had 2ton air and I believe around 60,000 to 70,000 btu furnaces.
The unit I am looking at is a 2ton with a input heating capacity of 69,000btu and output of 55,000 btu. The indoor fan pushes 845cfm, and I was thinking of using 16" for the main trunk and return.
Does this info help?
Thanks, Dave

 

[OKnewguy]

The return is only in the one room, but the doors are never closed. My mom is the 3rd tenant in 8 years and all of them never close the doors. I know I should not take this as fact thou and will consider adding some additional returns.
I originally thought about ductless mini's and have researched them to no end. I have even talked to a few heat and air guys over the years, and most have little to no experience with them, so I am a little nervous about going with them. The better ones are supposed to function down to 0, but even that has me worried about needing some additional heat occasionally in the winter. I gathered Mitsubishi was a very good brand. What are your thoughts? Have they proven to be reliable?
Thanks, Dave

 

[OKnewguy]

I even am tempted to get 2 of these units. Do it yourself air conditioner, DIY mini split, DIY room air conditioner, self install AC
They are supposed to be 100%diy, and have a special line set that is already vacuumed and charged. You basically plug them in and lock the lineset together, hook up the power and you are ready to roll. I just don't know about the brand.
Dave

 

[dlauffenburger]

I installed a Mitsubishi mini-split heat pump system in my garage and have been impressed and pleased with the results. You provide one 220V power line to the outside unit and it supplies the DC voltage to the inside unit. It is extremely quiet. I am not familiar with your weather cycles so you need to make sure that the Heat Pump system will provide the heat you need. I think I read that you can get them with a seperate heat strip if needed, not possitive, you can call the Mitsubishi Help line and get specifics.

I was able to order the unit on the internet and get it delivered with everyting needed for about 60% of what the local Mitsu dealer quoted me. He wasn't pleased that i ordered it over the net but understood why and couldn't complete with the price, he doesn't order enough units to get the discounts. In order to get the warranty you have to have it connected by a liscensed A/C tech, so i called a local guy and made arrangements. I installed everything except the connection of the refrigerant lines to the outside unit, he came by and inspected everytbing and performed the connection of the line set for $100 and signed the warranty card.

Dave

 

[sandman2234]

One way to realize that designing and installing duct work isn't as easy as it looks would be to find a "ductwork problem" help board and start reading just what people suggest could be wrong with your ductwork.
I was a driver from a sheet metal duct manufacturing company and would help in the shop when I didn't have a run to make. I saw a lot that went into making it, but learned that making it was the easy part.. designs were what made or broke a system.
David from jax