Hydro air heat or not (conversion from steam)

Grant

In investigating AC solutions for our older home with single pipe steam heat, our HVAC rep strongly suggests to abandon steam and convert to hydro air heating thru central air ducts he would install.  He believes we'll see a 30-40% gas consumption savings.  Were not unhappy with the steam heat but a savings of this amount has peaked our interest.  We would like to know from the experts if this is reasonable savings to expect? (We live in Nassau County, Long Island.) By what percent do electric costs increase with this sytem?  Is this type of heat "nice" to live with?

Of course we could just keep the steam heat and add ductless units to cool the house.  We want to make a reasonable decision to position ourselves for lower over all untilities costs, if it is worth it.

Looking forward to your response.

Charlie from wmass

Repair the system and add ac

You can repair and properly size the new boiler and save 30% on fuel with many systems and keep the warmth of steam. you can install mini duct or ductless for ac and destroy a lot less of your home to have ac.

Grant

What are the advantages of they hydro-air heating?

Some clarification:  Our steam boiler is only a few years old and needs no repair.  We have been told that of all heating systems, steam is the least efficient.  Is our HVAC rep wrong in telling us we will save 30% - 40% if we convert the steam over to hydro-air  heating?

Is the heat produced this way comfortable?  

We have an old Moorish style colonial with a 16" attic ceiling height tapering down to 6" so mini duct doesn't work.  Also, we have many nice old architectural elements we didn't want to ruin by putting up the boxy looking units that come with ductless. 

JStar

Hmmm.

If the boiler is only a few years old, we might assume that it's between 70 and 80% efficient. How do you add 30-40% to that? I think it's all marketing.



Convection heating (heat transferred by air) will never be as comfortable as radiant heat. I would keep the steam, have it analyzed and set up for highest efficiency, and go with a dedicated A/C system(s). With hydro-air, you'll be running two units (boiler and blower) all winter, instead of just one boiler.

Grant

Does convection use less fuel to run than steam?

Is it possible that we will use much less gas (as it is a gas boiler) if we convert?  We are not really interested in converting otherwise as we have done quite a bit of work to make our steam system run efficiently. 

Charlie from wmass

depends on how

well your current system is running and how the boiler is sized. But 30% I very much doubt. How was the current boiler sized and do you have any photos of the boiler piping?

Jack

I'd skip the ducted system and go

mini-split heat pumps. First of all I represent Fujitsu, so bias noted, please. Having said that, I would suggest that you leave your steam system intact. Put in mini-split heat pumps. Do not change your system...add. Todays mini-split heat pumps are very high efficiency (varies by model) units and they are net conditioning to the space. In other words, no duct system losses. Your steam system is likely Waaay oversized so run the heat pumps in Sept, Oct, Nov, early Dec. When it gets really cold and you have a load against the boiler so it can run efficiently, turn it on. As soon as it warms up, go back to the heat pumps. You live in the house so you decide what your balance point is. And, you get very high efficiency zoned cooling and dehu. Buy it for the heating efficiency. The cooling is free.

It is very difficult to add an adequate duct system to an all ready built home. You pretty much have to tear the place down to get the duct work in. You loose floor space, closets and the system is difficult to seal up. I'm in the process of pulling all the retro-fitted duct out of my home. I am replacing it with Two Fujitsu heat pumps (up and down) and one Rinnai Energysaver. Again, I represent both these lines, but I'm going to save a ton of dough and be much more comfortable. In my home the retrofitted duct system heated and cooled poorly, was designed and installed poorly and it was like a darned typhoon in some places and no flow in others. Certainly, your mileage may vary, but over many years of looking I've never seen a really good duct retrofit. Adequate maybe, but never excellent. What do you want to pay for?

How big is your house? How do you use it? Do you want to condition all of the house all of the time or do you really only spend your time in specific areas? Run some numbers at www.miniheat.com

izhadano

what savings can be expected from heat pump

Comparative cost of useful unit of heat was calculated in 2001 and 2008 by Geo-Heat Center Oregon Institute of Technology for heating by fuel oil, propane, natural gas, electricity, air sourced heat pump- ASHP and geothermal heat pump –GHP.



I put these data into the table along with current prices for fuel oil, propane, natural gas, electricity for New England. You can do the same for your area. The following math was pretty straightforward but results will, probably, surprise you.



Attached is a file with GHP basics, calculation method and  comparative table with results (links are in blue).

I wonder about your conclusion ....