# New HVAC-Northern California



## peachtree (Oct 7, 2016)

Hi All, 

I've been working on my house for the last year or so and now it is time for a new HVAC system. We live in Santa Clara, Ca and the house is a small 1,150 sqft with one story and ok insulation.

Attached you'll find the house plan and the layout i've composed of the duct so far. 

So far the comments I have are: 

1) Need a larger return grill
2) Add mechanical dampeners to all Wye. 

You comments and concerns are welcomed. 

Thanks,
V


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## nealtw (Oct 7, 2016)

Welcome to the site.
I can't add usable info but for the unit in the garage, it wants to be air tight from the garage so there is no auto off gasses getting into system.


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## peachtree (Oct 7, 2016)

@nealtw, thanks.

The garage is being used as a lab so no other gasses are present.

I would like to start the duct work this weekend as the evening are becoming much colder. 

Thanks,
V


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## peachtree (Oct 7, 2016)

nealtw said:


> Welcome to the site.
> I can't add usable info but for the unit in the garage, it wants to be air tight from the garage so there is no auto off gasses getting into system.


Thanks NealTW. Garage is used as a lab a no other gases are present.


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## Snoonyb (Oct 7, 2016)

Regarding the garage equipment.

The truly left coast has specific covered off-street parking requirements, so if you planning this equipment installation yourself, you will have to justify those requirements to the building authority and they will be depth and a bollard protecting the equipment, if the depth is correct.

If you are subbing to a contractor, they will know and advise you.

The comfort heating and A/C "A" coil are generally encased in one piece of equipment, with a fresh air ducting to natural air, and the compressor dislocated externally.


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## Snoonyb (Oct 7, 2016)

peachtree said:


> Thanks NealTW. Garage is used as a lab a no other gases are present.



Be very careful, because if you do not meet the parking requirement, somewhere on the property, you'll be in for a costly surprise


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## peachtree (Oct 7, 2016)

Thanks Snoonyb. I'll keep that as my one items to check. 

Any concerns on  the duct sizing and placement. 

I'm thinking on locating another return in the living room area. This way I can up the return grill up to 600 in^2? Location would be in the living room next to the other return grill on the hallway. 

Thanks,
D


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## nealtw (Oct 7, 2016)

Snoonyb said:


> Be very careful, because if you do not meet the parking requirement, somewhere on the property, you'll be in for a costly surprise



He just needs a smaller car.


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## Snoonyb (Oct 7, 2016)

nealtw said:


> He just needs a smaller car.



It would be nice if it were that simple, in some municipalities the planning director will permit one of the spaces, when two are required, to be compact, and the OP has the opportunity to apply for an exception to the ordinance, for a substantial filing fee, surveying his neighbors within a designated radius from the corners of his property and then waiting for the planning commission to put the Item on the next planning commission schedule.

That's generally how it works, on the truly left coast.


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## Chris (Oct 7, 2016)

I'm not 100% but I believe in California it is against code to have ducting from garage to living space unless it was a permitted remodel and can never be used for parking again.

Here in so cal near me you need two 9'x 15' parking spaces minimum. Could be different where you are.


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## nealtw (Oct 8, 2016)

Chris said:


> I'm not 100% but I believe in California it is against code to have ducting from garage to living space unless it was a permitted remodel and can never be used for parking again.
> 
> Here in so cal near me you need two 9'x 15' parking spaces minimum. Could be different where you are.



Here we can do it if we close it up and have access from the house or an exterior rated door for access from the garage, trouble is most of the time they end up with double doors as you try to keep it as tight as possible.


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## Snoonyb (Oct 8, 2016)

Chris said:


> I'm not 100% but I believe in California it is against code to have ducting from garage to living space unless it was a permitted remodel and can never be used for parking again.



The distinction lies in, "combustion air" and "conditioned air". There are thousands of single and multi family dwellings with either or both, HW Heaters and comfort air appliance located garages. While the conditioned air must be contained in a closed system, the combustion air can be taken from the garage because of the volume of available air and garages are not that tight. 



Chris said:


> Here in so cal near me you need two 9'x 15' parking spaces minimum. Could be different where you are.



Parking requirements will vary municipality, to municipality, and from vehicles must be in a garage, not in the driveway or on the street, too under a carport.


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## beachguy005 (Oct 8, 2016)

peachtree said:


> Thanks Snoonyb. I'll keep that as my one items to check.
> 
> Any concerns on  the duct sizing and placement.
> 
> ...



I'm just curious...how many returns do you have in total?


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## Snoonyb (Oct 8, 2016)

The balance is critical and the optimum is 5 air changes per hour, and the damper will give you a closer to finite control.


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## Chris (Oct 8, 2016)

Snoonyb said:


> The distinction lies in, "combustion air" and "conditioned air". There are thousands of single and multi family dwellings with either or both, HW Heaters and comfort air appliance located garages. While the conditioned air must be contained in a closed system, the combustion air can be taken from the garage because of the volume of available air and garages are not that tight.




So you are saying I was correct? You cannot have venting that connects house to garage?


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## Snoonyb (Oct 8, 2016)

Chris said:


> So you are saying I was correct? You cannot have venting that connects house to garage?



No, there are thousands of systems with the comfort heat appliance in a residential, in continuous use, parking garages throughout CA.

They are closed systems, taking only combustion air from the garage.

Not fresh air for conditioning.

The make-up air for conditioning is taken via a fresh air duct.


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## Chris (Oct 8, 2016)

I was under the assumption from my inspector that you can not pull any air from the garage because cars run in there and it is pumping poison into you house? I tried to add ac vents to my garage but was not allowed to.


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## havasu (Oct 8, 2016)

My A/C guy added ducting towards my garage so if I ever wanted cool air in the garage, I would just have to cut a hole and tie in a vent. I figured since their was no air intake, it would be permissible?


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## nealtw (Oct 8, 2016)

havasu said:


> My A/C guy added ducting towards my garage so if I ever wanted cool air in the garage, I would just have to cut a hole and tie in a vent. I figured since their was no air intake, it would be permissible?



And then , you don't have it running, air can move the other way.


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## havasu (Oct 8, 2016)

I see your point. Maybe this is why he wanted me to do the install.


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## nealtw (Oct 8, 2016)

havasu said:


> I see your point. Maybe this is why he wanted me to do the install.



And now we hear about cars left running by mistake.


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## nealtw (Oct 8, 2016)

Snoonyb said:


> No, there are thousands of systems with the comfort heat appliance in a residential, in continuous use, parking garages throughout CA.
> 
> They are closed systems, taking only combustion air from the garage.
> 
> ...



I would think they would be in a closed room, sealing around duct work would be a nightmare.


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## Chris (Oct 8, 2016)

I have never seen a furnace in a garage. Water heater yes but no furnaces but then again I live in California where everything is illegal.


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## Snoonyb (Oct 8, 2016)

Chris said:


> I was under the assumption from my inspector that you can not pull any air from the garage because cars run in there and it is pumping poison into you house? I tried to add ac vents to my garage but was not allowed to.



That's correct, because just dumping conditioned air into a space without a return, unbalances the system, so when someone either opens, or leaves open the pedestrian door to the enclosed parking area, the potential exists for contaminated air to be drawn into the conditioned air system.

Taking it a step further, the air duct feeding the garage has a damper so that you are not heating the garage, just cooling it. So with the damper closed, and they are inherently a loose fit, the redirected air flow may cause a slight vacume, drawing air from the garage.

Building codes are designed to protect you, from you.


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## Snoonyb (Oct 8, 2016)

Chris said:


> I have never seen a furnace in a garage. Water heater yes but no furnaces but then again I live in California where everything is illegal.



Look in any of the housing developments constructed in O.C, LA CO, VENT, Riverside and San Bernardino since the 90's.


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## Chris (Oct 8, 2016)

Three of my homes fit that area and all have the furnace in the attic. It would make sense to have a furnace in the garage but it would still have to be plumbed to pull air from inside the house and not garage air.

Wouldn't a vent in the garage without a return be the same as a vent in a bedroom with the door shut?


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## Snoonyb (Oct 9, 2016)

Chris said:


> Three of my homes fit that area and all have the furnace in the attic. It would make sense to have a furnace in the garage but it would still have to be plumbed to pull air from inside the house and not garage air.
> 
> Wouldn't a vent in the garage without a return be the same as a vent in a bedroom with the door shut?



There are a lot of that system as well. Its a lot more difficult to push warm air down and the return ducting needs to be sized for it.

Interior doors are loose fit and allow air flow, where a garage pedestrian door, because of the fire rating of the assembly, is a tight fit, by comparison.


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