Heating system and water heater choices

GurvyMarch 25, 2013

Posted this earlier in the wrong area, so I am reposting it here.

I am in the process of building a new home in the lower Hudson Valley in NY. We are currently in the decision making process for the HVAC system. Already met with the HVAC guy and he steered us towards Forced Air. Have had thoughts of putting in Forced air with an attached humidifier (Tempstar units - load calculations still pending) vs using the Hydro air for heating.

The other issue is whether using a Tankless Hot Water heater is an option for us if we use Hydroair or should we use a conventional hot water heater. I have had different people tell me that hydro is the way to go so I don't have to worry about humidifying the air and that a Combi-Cor compressed liquid propane Tankless system will be perfect for this, but then I hear the opposite from others.

The home is 4100 square feet - 5BR and 4-1/2 bath with a 2 story foyer and 2 story family room that will have a gas fireplace. The home will use Liquid Propane. The plan is to put 1 unit in the basement and 1 unit in the attic. We are also trying to keep the efficiency of the 2 units at about 92+%.

Any help will be greatly appreciated. If any other info is needed from me, I will gladly provide it. I will be arranging another meeting with the HVAC guy this week.

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mike_home

It sounds like you don't have access to natural gas, and you are considering propane as the fuel source. Do you know the rates for propane and electricity? It may make sense to get a dual fuel system of a propane furnace and heat pump. Post the rates so a calculation can be done.

If your house has a tight seal, then you may not need a humidifier. If you do add one to a forced hot air system is relatively simple and not very expensive.

Tankless hot water systems are very expensive, require routine maintenance, and don't save much in operating costs. You are better off in my opinion in getting a conventional hot water heater of 50 or 60 gallons.

Your HVAC guy needs to do a heating and cooling load calculation and show you the print out. It is very important this be done for a new construction.

    Bookmark   March 25, 2013 at 12:28PM
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fsq4cw

Have you considered geothermal? Yes it has the highest up-front costs but if you donâÂÂt have access to natural gas this may be the best option, particularly so if youâÂÂre considering any form of hydronic in-floor radiant.

Other possibilities could be a geothermal hybrid system utilizing a propane gas furnace for backup. One geothermal unit would provide forced air heating and cooling, full capacity hot water for radiant heating and most if not all of your domestic hot water.

You could also choose a Carrier Infinity Greenspeed heat pump system either an all-electric variable speed fan coil or gas hybrid furnace (propane) variable speed set-up.

SR

Here is a link that might be useful: Triple function geothermal

    Bookmark   March 25, 2013 at 2:07PM
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SnidelyWhiplash

Wouldn't you need to know how much OP pays for electricity before recommending any kind of heat pump? Doesn't that make a big difference?

The equipment brand you linked to (Nordic) is almost unknown in the US market. I'd think if OP wants to go in the ground source heat pump direction, he'd be better off using a better known brand.

    Bookmark   March 25, 2013 at 4:46PM
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Gurvy

I agree that LP is the not a great way to heat, but unfortunately that is the only available form available where we are building. It is a medium sized sub development.

I have been leaning towards the forced air with the humidification - I am unsure of the RH% in the home, but its not that good in the current home I am in and its only about 7 years old. My concern, if I decide to use a humidifier as part of the system, is whether there is any way to humidify without placing a humidifier in the attic to limit the risk of leaking and ruining my ceiling.

As for the price of propane, the place we will likely get the LP from is selling it for $3.309/gallon today. Electric is also not cheap in this area.

As for the Geothermal, I did consider it, but was a quick decision not to go that direction due to the high upfront costs that I cannot do.

    Bookmark   March 25, 2013 at 11:37PM
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fsq4cw

Snidely:

âÂÂWouldn't you need to know how much OP pays for electricity before recommending any kind of heat pump? Doesn't that make a big difference?âÂÂ

Not really. These are just suggestions of what may be possible. The OP can crunch his own numbers and draw his own conclusions. Besides, since active cooling MUST involve electricity and given that he lives in NY where winters are cold, the additional cost of a HP over an A/C only condenser may make sense. A hybrid system such as the Carrier Infinity Greenspeed with a propane gas furnace and a heat pump would essentially provide a near complete range of flexibility based on dual sources of energy as well as high efficiency.

A HP (even air-source) with a COP of 3 means that you can essentially divide the electrical rate by 3 to determine the âÂÂcost per kW of heat delivered into the homeâÂÂ. So even if itâÂÂs 24-cents per kW, the cost per kW of heat delivered into the home would be about 8-cents.

The OP would have a measure of shielding from energy costs as they could choose to heat with an electric heat pump of extremely high efficiency, 13-HSPF, or propane, which ever is cheaper. Should natural gas become available a relatively inexpensive conversion from propane to NG could easily be done. Any defrost cycles would be performed with staged propane as opposed to high priced electricity and resistance heating elements.

So no, I donâÂÂt see any problems only benefits.

As for Nordic, any other well-known brand could be used. One of the reasons for using Nordic links is that their site is well documented with a wealth of information that could be used with any brand HP that performs the same functions. See link below just as an example of the plumbing layouts and options alone.

The OP would be best off going with whatever equipment is commonly installed in his area and can be easily serviced by one of several companies operating there.

Gurvy:

Should you go the propane forced air route, I would advise installing the highest efficiency furnace due to the higher price of propane over NG (which is not available) and due the lower efficiency of propane over NG. You may as well squeeze out all the energy you can!

Regarding your humidity concerns, you may find that with a heat pump you may not need a humidifier as the lower temperature output of a heat pump does not dry out the air as does the higher temperature output of a fossil fuel or all-electric furnace. However, you may feel more comfortable at a lower temperature with a higher humidity level during heating season.

As for the attic, I would avoid installing HVAC equipment there altogether, if at all possible.

SR

Here is a link that might be useful: Nordic - Plumbing options and schematics for geo

    Bookmark   March 26, 2013 at 1:39AM
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david_cary

Well if the OP pays $.50 a kwh, than a HP is not a great option. There are areas in the US where this is true. Now - NY doesn't see those rates so you are absolutely right that a HP makes sense in a dual fuel scenario in all of NY when combined with LP.

Because LP is so expensive, it takes electric rates over $.30 to make a HP not viable. But I believe much of NY is close to $.20 so it isn't that helpful. But maybe the OP is closer to $.10, then not doing a HP would be CRAZY.

I totally disagree on the drying. A heat pump uses more air movement, which allows for more air leakage, which causes more drying....

    Bookmark   March 26, 2013 at 6:50AM
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mike_home

My suggestion would be to put both systems in the basement. This is how my house is set up and it works well if the duct work is sized and planned properly. It may cost a little more money up front, but you should make it up on lower operating costs.

You don't have to install humidifiers on both furnaces. A humidifier on the first floor furnace should be sufficient. The humid air will rise and circulate through the house.

    Bookmark   March 26, 2013 at 9:44AM
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SnidelyWhiplash

"Regarding your humidity concerns, you may find that with a heat pump you may not need a humidifier as the lower temperature output of a heat pump does not dry out the air as does the higher temperature output of a fossil fuel or all-electric furnace. "

This is not correct. To explain, if one were to open windows and fill the house with 35 degree (let's say) outdoor air. Case 1, the house is warmed with a heat pump that heats the air to 80 degrees. Case 2, house is warmed by a combustion furnace (of any kind) that heats the air to 105 . Ignoring air infiltration from a longer heat pump run (as David correctly points out), once the indoor air reaches 70 degrees, in both cases it will have exactly the same relative humidity. This is basic physics, not hocus pocus.

fsq4cw, your comments get tiresome.

    Bookmark   March 26, 2013 at 11:30AM
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fsq4cw

Snidely:

IâÂÂll be polite.

YouâÂÂre like a bad penny that keeps showing up after almost every post I make. Did I know you in a past life?

If you donâÂÂt agree or like my posts just skip over them and donâÂÂt bother reading or responding to them. IâÂÂll do likewise with yours as you have little constructive to contribute beyond criticism.

IMO

SR

    Bookmark   March 26, 2013 at 5:23PM
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weedmeister

You can call the local utility and get the electric rates. Just make sure you're getting all of it (delivery and generation charges).

    Bookmark   March 26, 2013 at 5:29PM
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ionized_gw

" you may find that with a heat pump you may not need a humidifier as the lower temperature output of a heat pump does not dry out the air as does the higher temperature output of a fossil fuel or all-electric furnace. "

Show me how this works. It does not seem correct.

    Bookmark   March 26, 2013 at 8:22PM
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SnidelyWhiplash

Gurvy - Good luck, hopefully you'll hook up with a solid HVAC contractor who will guide you to the right choices for your area and conditions.

fsq4cw- Absolutely let's be polite, good call.

I've questioned comments you've made when either you seem misinformed (as with your relative humidity comment above), or your answers seem more appropriate perhaps only to your Montreal hometown climate and utility costs.

Most people asking questions don't live down the street and around the corner from you. You know that. The best answers are the ones that have the broadest applicability, or are the ones that are tailored to the asker's circumstances. We can all do a better job with that, agreed?

There's no one size fits all.

    Bookmark   March 26, 2013 at 8:47PM
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fsq4cw

Ionized:

" You may find that with a heat pump you may not need a humidifier as the lower temperature output of a heat pump does not dry out the air as does the higher temperature output of a fossil fuel or all-electric furnace. "

âÂÂShow me how this works. It does not seem correct.âÂÂ

This is a subject matter that has arisen many times before during accreditation courses and seminars for professionals delivered by professional engineers and is applicable to all regions.

As a quick reference see the link below, âÂÂQuality of Life FactorsâÂÂ, Chapter 1, page 5 of âÂÂGeothermal Heat Pump Manualâ prepared for NYC Department of Design & Construction by P. Andrew Collins P.E., Carl D. Orio & Sergio Smiriglio August 2002.

See âÂÂTable of Contentsâ ii âÂÂCredits and Acknowledgementsâ to verify the credentials and professionalism of the authors.

While this does not explain the physics, perhaps you may accept that this might be true and seek to explore it further on your own.

SR

Here is a link that might be useful: âGeothermal Heat Pump Manualâ prepared for NYC Department of Design & Construction

    Bookmark   March 27, 2013 at 1:32AM
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ionized_gw

The writers all look like people that would have some benefit from the sales of ground-source heat pumps. There is no logical argument for what you or they have stated about better humidity levels while heating. Furthermore, I find their statement leading us to believe that better cooling humidity control can be attained are likely bogus. I don't see why an evaporator coil will operate at a lower temperature in a good system with an outdoor air-to-air heat exchanger compared to a ground-source heat exchanger.

I am not drinking that Kool- Aid.

    Bookmark   March 28, 2013 at 7:26PM
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