Fresh Air Intake on Steam System in New Construction

P1385

Howdy all! I'm in pre-design stage for a new home and am giving serious consideration to using steam for heat along with a mini-split for the cooling side. My question is, how have you worked the fresh air intake with a steam system? I understand how it works with forced air, easy enough, because air is being pushed around anyway, so we just have to knock a hole in the wall. No biggie!

How about steam? Thank you in advance!

RayWohlfarth

We have used these with success
Good Luck
http://www.fieldcontrols.com/cas-3-oil-and-cas-4-gas?page_id=94

Danny Scully

@P1385, where are you located? (Please say Long Island, please say Long Island)

Steamhead

Well, you asked..... Lawn Guyland, Lawn Guyland.......

Phil53

Steamhead said:

Well, you asked..... Lawn Guyland, Lawn Guyland.......

Very clever @Steamhead

leonz

P1385 said:

Howdy all! I'm in pre-design stage for a new home and am giving serious consideration to using steam for heat along with a mini-split for the cooling side. My question is, how have you worked the fresh air intake with a steam system? I understand how it works with forced air, easy enough, because air is being pushed around anyway, so we just have to knock a hole in the wall. No biggie!

How about steam? Thank you in advance!

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A small single steam system may or may not make the tight home too hot.


Have you seriously looked at a small gravity hot water as an option with your boiler since your planning on new construction??
As you are examining new construction as an option the use of a gravity hot water system would be easy to employ as the two vertical risers would be easy to install and be placed in a single utility chase that would feed all the hot water radiators from the two hot water risers and then to the returns to the boilers two cooler water drop pipes to the boiler sump tapping's.

If you plan on having an uninsulated attic you could have an open to air expansion tank in the attic with a loop pipe at the base of the open to air expansion tank to let the hot water heat the water in the expansion tank to prevent the water from freezing and allow the water to circulate faster to the top and then back down to the boiler sump tapping's.

The heat shed from the entire volume of hot water in a gravity hot water heating system is slow and even heat through the entire home when the water is heated and rises to the open to air expansion tank and falls by gravity back to the boiler sump tappings.
Many of these systems are 100 years old now and still working very well.

If your planning on a well insulated home gravity hot water will work very well too.

It has to be designed right to enable you to achieve the most efficient system and need to be designed by an experienced plumber or HVAC mechanical engineer.



About the combustion air inlet;

An unpowered option often done with wood and coal furnaces, stoves and boilers would be to simply run 4 inch PVC pipe from the exposed basement wall to near the air combustion air intake on the steam boiler where a 90 degree elbow pointed downward which is fitted with a fine metal mesh screen inside a plastic slit screen end cap connects to the PVC pipe that passes through the basement wall that is passed along the floor joists to near the steam boilers location on the basement floor where another elbow and length of PVC pipe is used to direct the fresh air to near the floor level air intake panel of the steam boiler.

The trick is to be sure the intake air inlet is well above the seasonal snow depth to prevent oxygen starvation of the boilers combustion air in the fire box and possible CO poisoning-the air inlet has been run up the wall a few feet and then 2 more 90 degree fittings with the final 90 having been screened, a short piece of PVC pipe is used to push the air intakes 90 degree and screened fitting away from the exterior wall.

STEVEusaPA

P1385 said:

... I understand how it works with forced air, easy enough, because air is being pushed around anyway...!

Actually I'm afraid you don't know how it works.

The 'air' being moved by the furnace blower motor has nothing to do with combustion air.

Combustion air requirements are sized by btu's of appliance and the code standards set for louver placement.

If the room is starved for combustion air, then something like @RayWohlfarth mentioned is the way to go.

If it's a big leaky house, no serious exhaust fans, or whole house attic fan, the basement might have enough air, or just adding a grate to the exterior, or putting a louver vent in a basement window could do the trick.

P1385

Thanks all! I see now that I wasn't clear on my meaning with fresh air intake. My question is how fresh air for the living space is brought in with a steam, or for that matter hydronic, system; not fresh air for combustion. My limited understanding is that with a new, tightly built home, fresh air needs to be introduced to exchange with humid indoor air.

Thoughts?

Zman

The old mansions used steam radiators hung in vertical chases which were open to the outdoors at the bottom and to the space on the floors above. This created a natural convection of warm 100% outside air for the occupants. This was refereed to as indirect radiant.

With today's tight homes, this would normally be accomplished using an HRV or ERV to steal most of the energy out of the air leaving the house and partially temper the air coming in. A furnace or fan coil would temper the air to the correct temperature before discharging it into the space.

RPK

https://www.greenbuildingadvisor.com/article/zehnder-develops-a-ductless-erv

An HRV or ERV is probably the way to go, ducted or “ductless”. It doesn’t really need to integrate with your heating system directly, but fresh air supply air outlets need to be located carefully, where they won’t blow on people. Even after the “energy recovery” process, the fresh air may be a bit chilly when OA temps are low.

gerry gill

My advise is don't build the house so tight that you have to bring in outside air cause someone farted

JUGHNE

Are there small power burners that have combustion air piped directly to them?
I have had combustion air problems for WH's in fairly tight basements.
Just the dryer, range hood and bath exhaust fans created an issue.

gerry gill

If i'm not mistaken, he is not talking about combustion air here, but fresh air.