Residential HVAC design services needed..... (sales, 2014, house)

[Starglow]

My 2-story home currently has two HVAC systems and one of them needs to be replaced. Due to old age and poor efficiency, the duct work for both systems also needs to be replaced which is very expensive.

Instead of installing new duct work for two separate systems, I'd like to have a new HVAC system design drawn up using only one new HVAC system and associated duct work to handle the entire home for both heating and AC.

I'm not looking for a salesperson pushing their company and preferred brand. What I want is an unbiased comprehensive professional design work up that can then be put out for bids based on the design specifications.

Any potential leads or suggestions would be appreciated.

Thanks in advance! 8-)

[guest12]

Sorry - I posted for a company that would do the design, but I doubt they'd then let that go out for bids.

[Starglow]

Originally Posted by guest12

Sorry - I posted for a company that would do the design, but I doubt they'd then let that go out for bids.

I have to do it that way because every company that comes out tells me something different in part because they are sales people and not HVAC designers which makes it difficult to get straight answers regarding exactly what they are proposing.

[frankpc]

You can ask for a Manual J calculation of the required capacity, but even that assumes the proper inputs are used. I've never met a residential contractor that provided one but I'm sure they're out there.

Just being curious here - why are you looking for a single zone system? How are you planning to deal with the different heating/cooling loads in each story of the house?

Frank

[Starglow]

Originally Posted by frankpc

You can ask for a Manual J calculation of the required capacity, but even that assumes the proper inputs are used. I've never met a residential contractor that provided one but I'm sure they're out there.

Just being curious here - why are you looking for a single zone system? How are you planning to deal with the different heating/cooling loads in each story of the house?

Frank

Dual zoning can be used to control different areas. Manual J has already been done and size capacity isn't the issue.... the duct work design is the problem.

[Sayantsi]

I think you'll get two stories - dual zone or active ducting. I'd go with active ducting since its simpler and allows you to push the conditioned air to where its needed most by season (AC upstairs in the summer, heat downstairs in the winter).

As for who to talk to, the general rule seems to be avoid Weather Masters at all costs. Comfort Engineers are purported to all be actual engineers and will do the whole system from your pack to the ductwork and will balance the house, but they are pricier than others.

[Formula88]

One thing you might try is contacting Wake Technical Community College, or another trade school with an HVAC program, and ask if they would be interested in using your home as a design project. I took HVAC service training at Wake Tech and we did just that with several private homes. The advantage is you get people doing it the "right" way because they're learning how it's supposed to be done, rather than taking the shortcuts that typically get taken by business to save time. (lots of gross estimates instead of actual calculations) As far as I know, this was all done for free with the homeowner only paying for the hardware.

[Ed_RDNC]

You say that you are unhappy with the configuration of the ductwork, but have you considered that running new ductwork through new pathways will require substantial modifications to your house? Duct chases and furrings to get from the new units location to all the rooms will be very disruptive and expensive.

EQUIPMENT:
First, you need to see if you have the physical space for the indoor unit. The new combined unit will be much larger than the existing unit. If the current unit is in the garage, a newer, larger unit might protrude into your parking space. If you want to put the new combined unit in the attic, is there that much more space up there? is there a way to get the large components up into the attic?
Also, if you come back with a single unit for the house, you will need to replace the two outdoor units with a single large unit too. (That is VERY expensive).

DUCTING:
If you (for example), want to abandon the attic unit and put a double sized unit in the garage, then you will need to have a large duct to run from the new unit up through the first floor and up through the second floor into the attic, (to where the ductwork will naturally want to be located for branching out and down to the second floor rooms). If you can see one of the current units supply duct connection, then that would be about the size of the ducting that would have to be run from the new, single unit, up (or down) to the alternate floor, taking up living space floor area. And since the combined unit is moving twice the air (versus the ground floor only unit), you will have to double the size of the return pathway too. If you have a wall grille from the house back to the current unit in the garage, then the grille and ducting would have to be doubled, to accommodate the added air flow from the second floor.

DESIGN:
All the above would not only take an HVAC designer to select the appropriate unit and lay out the ductwork, but also an architect to plan how to cover up the new ducting. And all that new duct routing will cost a lot, since a mechanical contractor will be doing custom work, not just the normal house install. Likewise the contractor will need sheet rock, painting, etc for all that extra duct to be covered.

COST
I know you said that replacing the existing ductwork and one of the systems needs to be replaced, and you are concerned about the cost, but I am totally sure that what you are envisioning would be substantially more cost. (Like twice or three times as much).



What you are considering is similar to trying to take a rear wheel drive car and replacing the engine with a front wheel engine and drive. It could be done, but only with substantial modifications that normally isn't done to a car. Same with your house. A residential house is designed to be used as is, with minimal flexibility for basic modifications. You can't move load-bearing walls, bathrooms, double the size of the kitchen, etc, without spending tens of thousands of dollars in a major renovation.

[sacredgrooves]

Is there easy access to the ducts you want to replace?

[Sherifftruman]

Personally, I would really shy away from a dual zone system to replace a two unit system. You still need a certain compressor capacity to cool all that area and the system needs to be able to either run at half capacity when one floor does not need heat or cooling or one of those areas might not be getting the heating or cooling or lack therof that it needs. Plus all the complications that Ed_RDNC came up with.

With the new 14 plus SEER systems, they are really much more efficent than what they are replacing. I would jus treplace what is dead (and maybe the other one if it is 15 years old) and have them check the ductwork to make sure it is OK.

Why do you have the idea that the ductwork needs to be replaced anyway?