Whole house reno - Going from old hot water to Gas Air.

sirspe · January 2013

I'm sure this sort of question is asked all the time:

We're adding a 2-story 20 x 24 addition to our 1700 sq foot house (build in 1930). We're mid-renovation (and our old furnace and radiators are gone).

The previous owner already had gas coming into the house.

We want to add A/C.

We're gutting much of the existing house and building the addition from scratch...

... so making the switch seemed to make sense.

Our contract is for two 95% (or higher) units - 1 in the basement for the 1st floor and 1 on the 2nd floor (or possibly the attic) to serve the 2nd floor.

And, of course, we have a limited budget. Any extra $ we spend on bells and whistles here are taken from other things in the house.

My 2 questions:

1) Are we going to be happy with 95% efficient system or is it really worth the bump up to a more efficient system with more features?

2) My biggest question: What about humidification??? I live near Boston and the winters are dry. We've heard every recommendation: Absolutely get some humidification... Only get it in the basement unit because we don't want an additional water liability on the 2nd floor (or attic)... Don't get any humidification because adding moisture to the ducts will severely shorten the life of the system... Instead, add a steam humidification system to avoid water in the ductwork.... Just buy a few humidifiers throughout the home and call it a day.

So, what to do?

Steamhead · January 2013

You should never

have gotten rid of the radiator system. No ducted system will ever equal the comfort and efficiency of radiators- especially since the typical duct system loses 20% of what goes into it. If the radiators have already been scrapped, you've spent a lot of money to have them removed and replaced by something that's going to cost you more money to operate, whichever furnasty you get. So you're screwed.

CMadatMe · January 2013

Agree with Steam

Should have never removed the hydronic system. Provides much better comfort way more efficient. Don't be fooled by AFUE because it has nothing to do with total system efficiency. It's only combustion efficiency. How efficient you can make energy is fruitless if the deliver system is inefficient. Welcome to forced hot air.

sirspe · January 2013

Whole house reno - Going from old hot water to Gas Air.

I appreciate your advice, but I'm looking for help going forward.

I wanted to update our inefficient system. I wanted to get rid of the oil tank. I wanted to get rid of the hot radiators in every room (taking up living area and forcing some floor layouts to incorporate hot radiators) . I wanted to add A/C. I believe there are advantage to hot water and radiators (I really do). The previous owners already have natural gas coming into the house.

Our major renovation were the right time to make a switch and Hot Air + A/C is the direction we're likely going.

My question was about incorporating some humidity for Boston winters. (I was led to believe this forum would have some valuable insight -- beyond "you're screwed")

But if someone has a strong recommendation for another direction for the whole system, I'd be happy to hear it. Thanks in advance.

CMadatMe · January 2013

Hydro Air

I'd look at doing Unico High Velocity for the a/c and add hot water coils for the heating being supplied by modulating condensing boiler.

sirspe · January 2013

Whole house reno - Going from old hot water to Gas Air.

Thanks Chris for the lead.

How does that compare in cost to Air? (not looking to skimp, just need to get the whole house done within our budget)

Would we need 1 unit for the whole house? Or 1 unit for each floor?

CMadatMe · January 2013

Don't Know

What you need. Would have to calculate a heat loss of the home as well as run the heat gain through the Unico software. No matter what type of system you choose someone must do a heat loss/heat gain to properly size the equipment. If they don't they are just guessing and you will most likely end up with regrets.

Henry · January 2013

Hot air

Congrats on getting a comfortable home using ventilaltion! You now can have the comfort of filtered air (dogs, cats and cigar smoke) with cooling in the summer and humid heat in the winter. We do a lot of high end housing in the Great White North. Radiant floor heating would be nice with a mod-con. A York high end hot air system with possibly (since in Boston) modulating heat pump would make your system efficient and comfortable. Don't forget to get a steam humidifier for the cold days.With such a small home even with the extension, you can do it with one unit! Or I can design you this: 23 radiant zones, duct heater, geothermal, steam humidifier, hot water and pool heater:

VictoriaEnergy · January 2013

Gone to air

Typically a single furnace could service a house of that size unless there were duct layout issues that excessively compromised that option. I don't like ducting in attics due to issues with insufficient air sealing and insulation. It's just hard to do thoroughly

95% efficient with two stage operation as a minimum, but consider springing for the extra of a modulating unit with Variable speed ECM Fan motor (not all ECMs are variable speed). All furnaces should be sized correctly, but this applies doubly for modulating units so look for a contractor who will measure up and do a heat-loss calc before starting the job.

sirspe · January 2013

Attic Install pros v. cons

We have a designated space in our laundry room for an upstairs unit (for the second floor). If we relocated it to the attic, we could use that space (in our laundry room) for a real linen closet (we wouldn't really have one otherwise in shared space upstairs).

We expected to have a humidity component to our system for the winter months, but each HVAC installer has advised against it (to our surprise). If we don't have humidity, then I figure the attic is a reasonable location.

As far as heat loss calcs, that's a little hard to do. Our 1666 ft house is old and fairly loose. Our 960 ft addition will be tight. We're going to add insulation to the original house, but not until the the initial HVAC is done... Always logistic issues during renovations, huh?

Thanks for your continued help.

John Mills_5 · January 2013

Low humidity

2 ways to solve. Humidifier and tighten the house. I agree, I wouldn't want a hum on an upstairs furnace. With humidifiers we find that it isn't a matter of if they will ever leak but when. I'd put a good one downstairs, a General 1099LHS is higher capacity than conventional hums from Honeywell or Aprilaire for example. And if you work to tighten the house to reduce infiltration, that likely will be all you need.

Being in scorched air country, we our customers are plenty happy with a properly sized and installed furnace. 2 stage (with 2 stage stat) and variable speed blowers a big plus. Having grown up in a house with "old hot water" I know how comfy that is. But if you want forced air, it won't be the end of the world!

Henry · January 2013

Modulation

I am a big fan of my York fully modulating system with outdoor sensor. it works fantastic both winter and summer anticpating the temperature changes while we are away during the day! i did not go the heat pump way as it is too cold during the winter for efficiency and then maintance. I have a two stage AC with a full mod hot air furnace.

Gordo · February 2013

Sirpe, Here's The Thing...

If you went onto a website that was for dog lovers, and you wrote something like:

"We moved into this house and found a dog in it. We don't like dogs, so we had it shot. What sort of cat should we buy?"

I suspect the responses would not be positive, wouldn't you?

You should know that this site is full of folks who are very passionate about hydronic heat, and the folks who remove said systems that they inherit and install "scorched error" are considered to have made a less than wise decision at best.

This, from a person who currently is suffering living in a house with "farced" air and, ironically enough, works on hydronic systems.

Whole house reno - Going from old hot water to Gas Air.

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