Converting to gas, replacing boiler, adding ductless multi-split or VRF AC & tankless hot water

CThomeowner

I wasn't sure where to put this, which is one of the problems I am having. As you can tell by my user name, I live in CT. Currently my house is a 1728 ft2, 4 BR colonial, built in 1966, with a 9' X 12' unheated breezeway & an attached garage. I have 2-zone (1 zone/floor), hot water baseboard heat, no AC, and my hot water is off of the oil-fired boiler, which was installed in 1996. I want to convert to gas for heating and hot water, so will need a new boiler (thinking high efficiency modulating/ condensing) and a tankless/on-demand hot water system. In addition, I want to add an AC system. Since I have low ceilings, allergies, & a husky/shepherd mix (for those who don't know, they shed massive amounts all year long-so not good for ductwork), I want to keep my hot water baseboard radiators and add a ductless system (8 indoor multi-split or VRF). I am also adding square footage to my house (216 ft2) and expanding my breezeway (to 9' X 32') & converting it to a heated space, which will include a bathroom and laundry.

From everything I've read, what is critical on all 3 systems (heating, hot water, & AC) is the proper installation. Additionally, although I have found some reviews on each system separately, there's obviously nothing on coordinating all 3 systems. So even if I were able to pick the best boiler, the best tankless/on-demand hot water, & the best ductless AC system (and that is a HUGE "if"), I have no idea whether they would still be the "best" choices when used together.

I obviously need advice from a professional. However, I am not sure how to select the best professional(s) for all 3 systems that I need. Here are some of my questions:
1. Since the functionality of each of these systems is so highly dependent on proper installation, should I look for an HVAC guy who is an expert in ductless AC systems, which seems to be the newest technology (and therefore the most difficult expertise to find ?), and assume he is also knowledgeable about the various boilers and hot water systems??? Or should I look for a company that has both ductless AC experts and boiler & hot water experts?
2. It seems as if most HVAC guys are trained/proficient in only a couple of brands and tend to promote those, even though they may not be the best option for my particular situation. Is it better to go with the system with which the installer is the most familiar even if it isn't the absolute best for the situation, or is there a great deal of similarity between the various brands, so if the installer is proficient at 1 or 2, he should be able to install a different brand of the same type?
3. My prime concerns in selecting these systems are efficiency, low maintenance, and reliability. I have found some information on efficiency, but almost nothing on reliability or maintenance of the various systems except from the manufacturers. Do any of you know where I can find impartial information on reliability and/or maintenance on the various brands of boilers, tankless systems, & ductless AC systems?
4. Since the breezeway is currently unheated, I will need a means of heating that area (and to a lesser extent cooling it). As I mentioned, with the expansion, it will be 1 story and 9' wide X 32' long. It will have a bathroom and laundry on the back of the house (the washer will be only 3-4' from the kitchen sink & all the plumbing fixtures in the bathroom will be only another 4-8 feet from the washer). The rest of the space will be mudroom, closets, & pantry - so no water. The problem I foresee with running the baseboard heat into the space, is there won't be enough places I could fit it to provide sufficient heat, which is especially critical in the bathroom & laundry. In the bathroom, which will be 9' wide by 8' long, I could only put ~5.5' of baseboard radiators. Would that be sufficient for the bathroom? There really won't be anywhere in the laundry area for baseboard heat. Do you think a ductless AC unit in the laundry area (which is off the kitchen, right before the bathroom), could provide enough extra heat on cold days and cool air on hot days? If not, any thoughts on alternate methods of heating that area? I do plan on adding spray foam insulation on the two 9' exterior walls & the garage wall plus the windows on either end will be low-E Andersen windows.
5. Do you have any suggestions on questions I should ask the HVAC folks to help me determine the best one(s) for the job? What specific things should I ask them to include in their quotes?
6. Any common issues that tend to arise in a house that's nearly 50 years old, which could impact my selection of systems and/or costs?
7. What size contingency should I have? Other than the back side of the 1st floor and the breezeway, where the walls will be exposed, refrigerant lines for the ductless AC will need to be installed into existing walls (down from the attic for the 2nd floor & up from the basement for the 1st floor). I assume that will be harder & therefore more expensive, plus there is greater potential for issues due to the surprises lurking in the walls of older homes. Would you suggest increasing the contingency due to that?

As you might be able tell, I need a LOT of guidance. I don't even know what it is I don't know! This is going to be a large expense and one that could cost me not only now but for many years to come and in many ways if I don't make informed decisions. Any guidance you professionals can provide will be greatly appreciated.

Rich_49

You don't need ductless trash in your house .

http://www.multiaqua.com/products.htm

After a competent heat loss calc of the house it may be determined that a new mod con water heater may heat your house . All you'll require is a decision on how many zones you want . Same outdoor unit (similar) receiving it's orders from a buffer or storage tank inside . No refrigerant inside the house and still no ductwork . Probably less first cost also .

You should probably have someone design a system then give those specs to your local guys so you know what they are bidding and you have an apples to apples comparison .
Don't fall into the tankless trap either , it's a numbers game . We can explain the numbers and what they really mean .

If you came here for the best advice you came to the right place . We may bicker amongst ourselves but don't go away . You can be assured you'll find everything you need right here .

Have you had anyone perform a building model or a heat loss calculation yet ? You definitely want Variable water volume as opposed to Variable refrigerant flow . Water will never be replaced by another type of water like is happening with refrigerants every couple years . Ther is your reliability .

Feel free to contact me at any time .

ChrisJ

@Rich

Do those have variable speed compressors?

Bob Bona_4

Long list, will give it a shot

SW CT contractor here, so these responses are regional for you and what's popular here in CT. No sense dealing with stuff no one stocks or uses.

It would be good to find a contractor with an "S1" liscense. They can do both heat and ac. Call a few and feel them out, ask if they are versed in mini splits, and mod con boilers as well. Eversource has a list of approved ductless heat pump contractors, that may be a good resource. If they do wet work too, even better.

We all have our favorite brands, generally we use what causes us the least problems Your equipment needs are not to crazy, although maybe rethink all those ductless heads and try hard to fit conventional ducting in, get a high quality air cleaner. The return and the air cleaner is really the only areas that get abuse. You'll have 8 head filters to clean vs. One, and some occasional return duct cleaning. 8 heads is , well, fussy.

It will be hard to find impartial recommendations on equipment. All I can say is to build trust with the contractor and make sure he stands behind his installation. I'v been doing this quite a while, so I have my own view of what's been working out well in the field.

A heat loss calculation is the first step in determining your needs, and it's a good sign if your contractor measures up rooms, doors, windows, pokes around in the attic to assess insulation etc. Good luck!

CThomeowner

First of all, thank you Rich & Bob Bona for responding and so quickly!

Secondly, I am a bit confused by some of your comments and could use further clarification.

You both seemed to think that I shouldn't go with ductless mini-splits for cooling. Rich, you attached a link for Multiaqua ductless chilled water air conditioning system. From that and your comments, it seems similar to ductless mini-splits with individual indoor units and 1 outdoor unit, but instead of refrigerant in the lines, it's chilled water. Is that correct? Can each indoor unit be controlled separately? Is the refrigerant the only negative of the ductless mini-splits in your opinion or are there others?

Bob, thanks for the advice on getting someone with an "S1" license and on using equipment that is locally available. Also, your point about having to clean 8 filters versus just 1 is well taken & not something I had considered. However, another reason I was looking at ductless is that the indoor units can be controlled individually. Some of my rooms such as my guest room, FLR & FDR are not used frequently. I wouldn't want to cool them whenever I needed to cool the rooms I use daily. However, I would need it when I have guests. When doing my research, I saw mini-ducts, which might be doable, but it didn't appear you could get the control the way you can with ductless systems. Am I wrong about that? Can you turn on/off the AC in individual rooms with ducted systems? What do you know about mini-ducts?

Rich, you mentioned that I should probably get someone to design my system. To show you how little I know, I thought the same HVAC guy who installed them would design the systems! Who would I hire to design the systems? A mechanical engineer? (Sorry if these are stupid questions!) Also, can you explain further what the problem with tankless hot water is? I essentially have that now with my hot water off of my boiler. I've never had a problem with getting enough hot water. Even with my older boiler, I only use ~50 gal of oil over the summer.

As far as heating is concerned, do either of you have an opinion on high efficiency, modulating, & condensing boilers? I know they are more expensive initially but are more efficient. Are there any reliability or maintenance issues with them? Are there any brands either of you would recommend? Bob, are there brands that are readily available here & work well in your opinion?

Finally, any suggestions on heating the new breezeway area? As I mentioned previously, it will be 9' x 32' & is located between the unheated garage and the kitchen & DR, so there's only the 9' on either end exposed directly to the exterior. The bathroom & laundry are on the kitchen side and the pantry & mudroom on the DR side. Because of the configuration of the area there's only ~4.5' in the bathroom & no place in the laundry where baseboard radiators can go. I can put baseboard radiators underneath the open shelving in the pantry as well, but I am less concerned about that area because there's no water there. A friend suggested radiant heat in the bathroom but it is expensive and I'm not sure how it would work with the rest of the heating system.

Once again, thank you gentlemen! I want to be as knowledgeable as I can be before I begin interviewing contractors & you have definitely helped.

Rich_49

Check out page 8 . Refrigerant inside the built environment does not sit well with me . The next big refrigerant already being used is Carbon Dioxide with pressures in the 1000s# . Won't that be good when the bargain hvac guy doesn't make a joint quite right . Water will as I said , always be water . The water coils will also vary output based on fluid temp and flow rate all the way down to levels lower than coil specs and the heating water can be made by a boiler or mod con water heater which will not decline in efficiency when it is getting colder outside when you need it most . You can cover the outdoor unit in the fall and see it next year when you need to chill water for your A/C .

Will address your other questions tomorrow .

njtommy

Honestly tankless hot water heaters are great, but you will never see your return on investment with them unless your running propane due to the cost of unit and installation.

Rich will I'm sure show and share some links with you on HTP boilers and combi units. They make units that are high efficiency like you are after that can handle both your heating and hot water needs.

As for you addition/ mud room. Radiant heating is a great option for that area.

CThomeowner

Thank you Rich and njtommy!

Cooling system
@Rich: While I won't pretend to fully understand the information on the Multiaqua system you provided, from what I could understand, it seems like a good solution for me. If you can bear with me, I do have a few questions:
1. Is Multiaqua the only manufacturer of this type of system?
2. Are the systems/parts readily available in CT? (This may be a better question for Bob Bona.)
3. Related to the previous question, is expertise in the the design/installation of these systems difficult to find? (Again, this may be a better question for Bob Bona.)
4. How reliable are these systems and other than cleaning the filters, what other maintenance is involved?

Hot water system
@Rich:
1. Was your only objection to tankless hot water that the return on investment was minimal due to the high upfront cost?
2. Was that what you meant when you referred to it being "a numbers game . We can explain the numbers and what they really mean"?
3. If you had other concerns, what were they?

@njtommy: I did consider combi systems but shied away for 2 reason:
1. My needs for hot water are fairly low, so I would not need a large system. When I go to sell my house, although I am not planning on doing so in the near future, potential buyers won't want to have to replace the entire system just to satisfy their need for more hot water. With separate systems they would only have to upgrade the hot water system to handle the greater demand.
2. If one of the system fails, both need to be replaced. (That's the reason I don't buy most combination electronics. I'd rather have separate components.)

So.....
1. In your experience, are these valid concerns?
2. What is your opinion of indirect hot water?
3. From my limited understanding, with an indirect system, if more hot water was needed, a larger tank could be added but the boiler would not need to be replaced. Is that correct?

@Rich & Bob Bona: Do you have any information/recommendations?

Heating & heating of breezeway:
Rich, Bob Bona, & njtommy:
1. Based on your experience, do you agree that a high efficiency mod com boiler is my best option? (I know I have to get an accurate heat loss estimate done but just based on your experience with the various types of gas boilers and a general idea of the size of the house, what would be your best "guess"?)
2. If so, do you have a favorite brand (or brands) and what is the basis of the selection (efficiency, upfront cost, availability, ease of install, reliability, ease of repair, maintenance, etc.)?
3. njtommy suggested installing radiant heat in the breezeway. How expensive would radiant heat be as opposed to adding baseboard radiators? (new plumbing would have to be run to the breezeway for either)
4. What if any issues would there be in using radiant heating in the breezeway with baseboard radiators in the rest of the house?

Again, thank you all for taking the time to respond and being patient with my numerous and extremely naive (sounds nicer than "stupid") questions.

Bob Bona_4

I'm aware of the Multi aqua product but I've yet to see any in my neck of the woods, nor are any of my 6 key distributors promoting them. So, for me, it's not an arena I'd pursue as a contractor bc I've other good hvac solutions.

Though I've installed many dhw tankless, in situations that make sense, my first choice is an indirect wh. I just like reducing the amount of burners/etc that add to complexity and maintenence. Best to size that indirect bigger if there's a high dump load like soaking tubs. Size boiler to heat loss and utilize storage is my mantra.

You need to get a heat loss done on the breezeway to reveal what type of heat emitter(s) will do the best job. You likely will find radiant lacking in power (btu) if it's like most breezeways- windows/wall exposure/ceiling/cold floors. The heat loss calc will clear some fog away Re direction to take.

There aren't any real dogs out there for mod cons, sized and installed correctly. Personally I avoid aluminum block units due to sensitivity to varying water chemistry. Stainless seems to hold up best from what I've experienced in the last 14 years of dealing with mod cons. Around here in rocky CT, anyway. I'm partial to Triangle Tube Solo series, they've served me well in the last 10 years or so.

Rich_49

Lots of questions , cool . At least you'll have a chance at getting something of value .
1. Is Multiaqua the only manufacturer of this type of system?

I am sure they are not . I have personally spoken to their staff and they offer unit verification at parameters lower and higher than their specs . The high wall unit looks just like the ductless evaporator but as the graph in the document I linked prior shows water is far more efficient from an energy use standpoint .

3. Related to the previous question, is expertise in the the design/installation of these systems difficult to find? (Again, this may be a better question for Bob Bona.)

Unfortunately design and installation that is good and proper is not the rule but the exception . Fortunately you have found heating help and there are many qualified designers here . Vetting contractors is the tougher part . Maybe you are near Bob Bona.

4. How reliable are these systems and other than cleaning the filters, what other maintenance is involved?

Not much to them to break .

Hot water system
@Rich:
1. Was your only objection to tankless hot water that the return on investment was minimal due to the high upfront cost?
2. Was that what you meant when you referred to it being "a numbers game . We can explain the numbers and what they really mean"?
3. If you had other concerns, what were they?
Tankless made it's name when the normal tank type water heater had a thin piece of fibreglass between the tank and the jacket , had a common burner at the bottom of the tank and had an EF of .62 . Those water heaters still exist but now have a thicker insulation so standby losses are not as great . Before the new Naeca codes took effect there were much better tank type heaters but were largely ignored by the purchasing public and the installers that were and still are scared to use a quality product . Better to put in lots of trash instead of using quality , gotta have every job . The average tankless you will find ranges from 140,000 to 200,000 and higher . It takes alot of energy to heat water from 55-60* to 120* in a matter of seconds . If you have a quality tank type water heater or indirect of sufficient size with a higher storage temp and mix down the burner will not engage quite possibly until you are 10 minutes into your shower . A 10 minute shower with the average 2.5 gpm showerhead requires 25 gallons of hot water , storing at 140* and mixing .75 gallons from the storage tank with .25 gallons of cold goes a long way . See the attached PDF

As far as the breezeway is concerned I would be inclined to remove the cladding below add the most R Value I could along with air sealing and install 1 -2 " EPS foam boards below the framing and re install the cladding . Then you can model that area to determine heat loss or you could just perform the heat loss as is and see what the traffic will bear.

I won't make any suggestions without enough information . What programs are available in CT through the utilities to get some of these tasks performed under the programs or at least get rebates and / or incentives for the work you perform .

http://programs.dsireusa.org/system/program?state=CT

Bob Bona_4

Good thought Rich. We do have a tasty $300 rebate going for ductless heat pumps, installed by (what do you know ) certified contractors. NG hi eff boilers were $750 rebate last year. Can't recall at the moment this year's incentives with that. $100 rebate on ECM pumps. No tax on Energy Star oil boilers. And other credits etc. That I'd need to dig deeper to verify. Long day.

Rich_49

Bob . The rebate is for the heat pump correct ? It makes no mention of fluid type ?

CtHomeowner . Does this home have a basement ? A usable attic ? Where is the boiler currently located ? How much fuel did you use last year ? Are you aware of the insulation values in the exterior walls, ceilings / roof plane , window type , doors ? What is the average temp in the basement if there is one ? there are so many questions

CThomeowner

@Bob Bona: Thanks!!

I have a well and live in New Haven County less than 3 mi from the Sound, if either of those things has any effect on your recommendations.

High hot water demands should not be an issue for me. There are no soaking tubs. I don't think I'd need a very large indirect storage tank.

So from what I gleaned from all the responses, I think that a high efficiency mod con boiler with indirect hot water storage is my best bet for heating & hot water. Any recommendations on indirect hot water tanks?

Since both you & Rich have suggested that expertise in design/ installation of Multiaqua systems might be very hard to find, even though they do seem to be the best option I've seen so far, I am leery of a system where expertise, parts & support are going to be difficult to obtain.

Are there any systems except the ductless splits that have individual room temperature control? Do you know much about mini-ducts? I don't think normal ducts will fit and want the least amount of installation issues but mini-ducts might fit and in theory would be easier to retrofit. I don't think they offer separate room control, which I really need, especially on the 2nd floor.

Thanks for your input!

CThomeowner

@ Rich Thanks again for your help!

In answer to your questions:
1. Does this home have a basement ? There is a full basement under the existing house. The current breezeway is on a slab, but I would want at least a crawl space for the new breezeway.
2. A usable attic ? Yes, there's an attic that an adult can almost stand up in. (There's batt insulation, but I don't know how much, since there's a plywood floor over it. I thought about putting more insulation but would have to remove the plywood flooring to do so.)
3. Where is the boiler currently located ? The boiler is in the basement, which is where I would have the new one located as well.
4. How much fuel did you use last year ? This past season, 8/14 to 8/15, I used 609 gal; the 2013 - 2014 season I used 525 gal; and the 465 gal during the 2012 - 2013 season.
5. Are you aware of the insulation values in the exterior walls, ceilings / roof plane , window type , doors ? I don't know there's batt insulation in the attic & exterior walls but I have no idea what the R-values are. I don't see any insulation in the basement. I replaced all the windows & doors a few years ago with Andersen Low-E windows & SGD (U factor 0.25) and a Stanley insulated door. However, the breezeway will be new as will the entire back of the 1st floor and I intend to use spray foam insulation on the exterior & garage walls, ceilings/roofs, and basement/crawl space.
6. What is the average temp in the basement if there is one ? I am not sure but I never saw it go below 55F in the winter or above 65F in the summer. There is an underground stream that goes underneath my house which makes it cooler but more humid in the summer.

Does that help at all in giving you get a better picture of the situation?

Rich_49

Ct . Do not lose sight of the fact that these hydro coils are only a heat exchanger and fan . There is not much that can or would go wrong . As far as support and availability of Multi Aqua stuff , they are available through Johnstone , Abco , Ferguson , R.E Michel ,Sid Harvey Universal supply , Luce / Schwab and Kase . This is not a product without support or representation . Maybe Bob would know more about the presence of these companies in Ct . I know Ferguson is there , they are everywhere ,Johnstone and Abco are certainly very visible in New York and RE Michel has a good presence also . I will attach another simple but good product . Simple is always good .

As far as the mini duct stuff goes you should look at Uniccoor Space Pak .

The slab on grade below the breezeway is a concern . The main concern is the water table . radiant should probably be discounted unless you will certainly make it a crawl . Nothing takes heat away fro an area better than water . water within 6' of a slab install can be terrible without proper insulation and plenty of it .

Basement is damp in summer ? Maybe a hybrid approach for year round use . You should look into installing one of these connected to your indirect . With low water use like you state this may be all you need to provide hot water , hold the boiler out from firing and remove humidity from the basement in summer . Read up on how it works , it is a 3 figure priced item . Another pretty simple idea that works well.

http://water.nyle.com/residential/

Bob Bona_4

Rich, I will have to research chiller rebates. I know there's some geo incentives, but I don't know if they lump "mini" chillers like the MA in the geo program.

We have the first 5 distro spread all over CT. In fact, I'm stopping at Johnstone today- need a new hygrometer for a problem humidity job I'm not thrilled to inherit.

The mini duct systems I assume are referring to high velocity. These have absolutely no room by room control capability. The closest you'll get to that with a conventional split is something like the Carrier Infinity system, with motorized dampers on each room duct runout. Rare in residential, quite involved.

My thoughts on the room by room control, for this house, is this: we have to look at the structure and dehumidification in the summer. If we were to shut down rooms, radically differently from occupied rooms, those rooms would not only rise in sensible heat, but humidity would be bleeding in. I don't feel that is beneficial from a comfort standpoint, or for the health of the structure. First floor/second floor/large areas zoning is more sensible, to me anyway. That's just my opinion, and it's probably not stated as eloquently as I'd like

CThomeowner

@Rich
When I decided to expand the breezeway and move the bathroom there, I knew I'd have to get rid of the slab and have a crawl space at a minimum, preferably a full basement (if the cost isn't prohibitive-still working numbers). I also intend to insulate the daylights out of it. The current structure, which is only 9' x 12', is unheated but open to the kitchen. It has my washer & dryer on the kitchen wall & a pantry on the garage wall. While it is usually a few degrees colder than the kitchen, I've never had an issue with freezing pipes, even without heat & being on a slab. However, I would never put a bathroom on a slab.

As far as Multiaqua availability is concerned, Bob has yet to see any & none of his 6 key distributors are promoting them. I checked out the distributors you mentioned but it doesn't look good:
* Ferguson, Johnstone, RE Michel, & Sid Harvey- Have nearby locations but don't list Multiaqua among their product lines.
* Luce, Schwab and Kase (LSKair) & Universal Supply - Lists Multiaqua among their product lines but only have NJ locations
* Abco - Lists Multiaqua among their product lines but only have NY locations.

However, even if I could find a local distributor, that still leaves the issue of finding someone who's qualified to properly design & install it. I couldn't find anything on the Multiaqua site where they list qualified technicians. Also I only get the CT rebate if I use one of the contractors from their list of approved installers. Bob made the point in his 1st response, which is an excellent one IMHO, that since all these systems are so dependent on proper installation, I should stick to those that are readily available and with which the potential installers have experience. Ideally, I'd like one person to design & install the heating, hot water, & AC systems so there is an overall HVAC plan. At this point, I am looking at a high efficiency mod con gas boiler with indirect hot water and since Bob suggested that most of the stainless steel boilers are fairly comparable, going with the system the HVAC I select is most adept at designing/installing. What I don't know is what type of cooling system would be best and therefore what expertise to look for in selecting the HVAC guy for that. Bob made some points re: the individual room control, which I will address in my response to him.

Thanks to you, Bob Bona, & njtommy, I am almost to the point of starting to interview HVAC guys & have much better understanding (although still not very good, sadly) of the capabilities of the various systems. This has been exceptionally helpful.

Rich_49

Design can be done from afar . Before you start interviewing those contractors / installers it would be a good idea to have a proper design and specs in hand . This way everyone you interview will be bidding the same job . They can use their boiler , their indirect but it must be plumbed and set up for the design . Anyone who won't install the size or type equipment spec'd , you don't want anyway . Apples to Appples is best . That third P was not as mistake either , some things look the same or will be overlooked which makes them completely different . Very easy for 2 contractors to recommend 2 totally different systems while they sound much the same .
Some mod cons need primary secondary piping , some don't . Many will require a buffer tank but odds are 98% of the time you won't receive one . You can easily be told you need an indirect bigger than you really do . There is so many things that can and do go wrong .

Bob may very well be able to perform your heat loads and design , hell maybe even do the install . Design services that are free are scary . Quite a bit of work goes into design and quality designs are never free .

CThomeowner

@Bob Bona

I never thought about humidity issues caused by air conditioning only 1 room!

Currently the only room upstairs that REALLY needs AC is my BR, but that will likely change in the next 2-3 years when my next phase of renovation occurs. (I will be converting the smallest BR into a master bath & WI closet off of the current guest BR and that will become my MBR and my current BR will be the guest BR.) At this point, the guest BR & my office (now that I am no longer working from home) get little use . HOWEVER, without AC, there are many days during the summer where those rooms are basically unusable IMHO because I can't stand to stay in them. On the other hand, paying to cool them on a daily basis seems a total waste of money. As does cooling the formal DR & LR downstairs on a daily basis, since they also are not used every day, but do need AC when they are used in the summer.

Till now, I have been putting in/taking out window AC units every summer. They are heavy, especially the large one for the FR & kitchen and don't do a great job because of loss around the units. Plus, after falling with 1 & nearly dropping them out of the windows on a number of occasions, I started paying someone to put them in & take them out for me. Unfortunately, he moved away, so I am back to doing it myself. I only put the AC in my BR this summer so during the hot, humid days, I am relegated to my BR!! Not a great long term solution!

I would think that running the AC in the office with something like a mini-split would be similar to my running the window AC in the office only. It doesn't seem to have been a big problem, although I certainly felt that blast of hot air when I left the office! The same holds true for my BR at night; the only window AC that I run at night on the 2nd floor is in my BR, unless I have overnight guests.

Also, if having one room air conditioned while the others are not causes humidity problems, wouldn't having a temperature/ humidity differential between the floors cause the same problems? Even if I had just the 1 zone /floor, I wouldn't run both floors all the time. I'd only run the 1st during the day & evening & the 2nd at night when I slept. So there would constantly be a differential between floors.

Perhaps I should scrap the idea of whole house AC altogether & just look into portable units for the FR/kitchen, my BR, & 1 for the office & guest BR. I know they aren't efficient but I think it would still be far less expensive than cooling the whole 2nd floor, when only 1 BR is used most of the time, and the whole 1st floor when 1/2 isn't used most the time.

Rich_49

Problem is that with high SEER equipment and a small room they will quite possibly never run long enough to remove that moisture . That's why I prefer water . If not Multi Aqua , research another brand of hydronic coil .

ChrisJ

Rich said:

Problem is that with high SEER equipment and a small room they will quite possibly never run long enough to remove that moisture . That's why I prefer water . If not Multi Aqua , research another brand of hydronic coil .

Rich,

You mentioned this the other night.
Why does SEER effect how long a unit takes to do it's job? Isn't a 1.5 ton unit a 1.5 ton unit no matter what it's SEER is?

Bob Bona_4

Do your interviewing, and report back I don't know anyone up your way, I'm one county over.
Try to keep it to 3-4 outfits. More than that is info overload.

CThomeowner

@Bob Bona Too late! I already reached info overload sometime ago! Seriously, it's been quite the learning curve for me but I do feel MUCH better informed. At least I am almost to the point where I almost know what it is that I don't know! Believe it or not, that's a big improvement!

Thanks for all your help!

Rich_49

If the loads are not done right a 1.5 ton becomes a 2 ton . Even if the unit is sized right we are speaking of ductless mini splits . In a single room a high SEER unit will satisfy the sensible load before it runs long enough to take care of the moisture . That's why there are so many house now with a 68* temp inside the house to feel comfortable . Right design and sizing will have you at the same comfort level at 72 - 74 * without the latent still hangin in the space .
Couldn't really know without calc done for that room or area

njtommy

I'm not sure if it's really worth shutting down rooms in the house that are not being used for ac. I know it seems silly to you, but a lot of these new units are modulating and are not energy hogs. Especially if you looking at units that qualifies for rebates. Most of those units are 18 seer or higher.

You can do a nice ducted system with zone dampers and just do upstairs and down stairs. The nice thing is with a ducted system you can also have humidity control all year round among air pure filers to knock down any dander from your pets.

You have a lot of opinions don't rush it.

njtommy

Also have you contacted the gas company to see how much you will be paying per therm delivered?

JStar

Isn't SEER the amount of BTUH/KW? I don't understand how that affects humidity or latent load either.

Bob Bona_4

In CT it's 14.5 SEER/12 EER for $250 rebate. I get the AHRI cert with a variable speed AH/14 SEER condenser. Boosts the rated SEER to 15.5 with most matches. Ductless heat pumps 20 SEER/10 HSPF minimum for $300. Single indoor unit.

I do a lot of the Fujitsu RLS3 units. Heat to -5 outdoor. 29.3 SEER. Amazing units.

njtommy

I believe what @Rich is saying is that the higher seer ductless units will modulate up to 100% to satisfy the load, but don't run long enough with cold enough discharge air to pull the humidity out of the air/ house.

Bob Bona_4

I'm seeing 47 degree discharge air give or take on the Fujitsu. Probably the same on the other brands due to the EEV's.

Rich_49

Yes Joe , that would be correct . They use less KWh because they run less time . They take care of the sensible load real fast , change air temp , then they shut off .
Just like a ducted high SEER that is oversized . One would be better off with a 13 SEER unit that is right sized as opposed to a high SEER unit that is a bit big . John has some pretty impressive pix of a year old house where everything rusted that was supposed to be stainless after 6 months . Funny how we did not see mold as much in houses before the High SEER stuff . It acts as if the house had radiant cooling without anything to remove the humidity if that makes any sense . Ever been in a house hat was 66* and the registers were dripping ? Guess why .
Not as much of a problem in these new really tight houses because less moisture enters because of improved vapor barriers and control layers .

ChrisJ

Rich said:

Yes Joe , that would be correct . They use less KWh because they run less time . They take care of the sensible load real fast , change air temp , then they shut off .
Just like a ducted high SEER that is oversized . One would be better off with a 13 SEER unit that is right sized as opposed to a high SEER unit that is a bit big . John has some pretty impressive pix of a year old house where everything rusted that was supposed to be stainless after 6 months . Funny how we did not see mold as much in houses before the High SEER stuff . It acts as if the house had radiant cooling without anything to remove the humidity if that makes any sense . Ever been in a house hat was 66* and the registers were dripping ? Guess why .
Not as much of a problem in these new really tight houses because less moisture enters because of improved vapor barriers and control layers .

You could run any size unit you want in my 150 year old house and not get mold.

Correlation does not imply causation.

Homes are also much tighter now.

JStar

So, you're saying that SEER rating is mainly determined by run time? There isn't any mechanical or control reason?

BobC

I looked into SEER vs EER a couple of years ago and so far as I can tell it is an specification that can be used to put lipstick on a pig. SEER is based on a single temperature that probably does not apply to 90% of the zip codes in the country. I think EER was a much more meaningful yardstick. You can find EER numbers on the new AC's but you have to hunt high and low for it.

I have a 14,000 BTU window AC on the first floor of my house (about 625 sq ft), that 10 year old unit was rated at 10.5 EER. Thirty years before that I had a different brand 14,000 BTU unit that had a 10.0 EER, both units were the most efficient you could get when I bought them.

As far as I can tell the only benefit the new units have is the ability to modulate, the base efficiency is perhaps 20-255 better than what was available 30 years ago. The key is they have to be properly installed to work correctly,

If you examine the specs carefully you will see a given compressor unit is most efficient at the low end of it's range (the same compressor unit can often be used to deliver 9,000, 12,000, or 15,000 BTU's (with different freon levels). The benefit of good window AC's is that they just work and they cost 75% less to buy; but they are 20-25% less efficient than the most efficient units currently available. Mini splits and central AC units need a lot more TLC that window units. The problem is large capacity window units are so damn heavy.

You have to choose between cost and convenience, I know I can no longer get a 14,000 BTU AC into the window on my own at my age.

Bob

JStar

SEER can be tested and calculated in the field. Albeit at one particular moment in time. I'm just not following the logic that runtime affects the SEER. A 25 SEER system running for an hour uses less energy than a 10 SEER system running for an hour. And the same goes for 45mins, 30mins 15mins, and so on.

And don't ductless systems modulate based on return air temperature, so technically they are always the correct size (within a certain limit)?

Rich_49

Changing the temperature only has NO effect on dewpoint .

ChrisJ

Rich said:

Changing the temperature only has NO effect on dewpoint .

That statement is incorrect. If it was correct, dehumidification would never take place.

That said, I was hoping you would explain why high SEER units don't remove humidity, or at least not well?

A 1.5 ton unit with a SEER rating of 29 should remove humidity the same as a 1.5 ton unit with a SEER rating of 5. Why wouldn't it?

JStar

Rich said:

Changing the temperature only has NO effect on dewpoint .

Why not? What does?

Tim Potter

Lots of info here:

https://en.wikipedia.org/wiki/Dew_point

Rich_49

Just as with our heating systems and all the nuances that get ignores by many , there is more at work than we think about . We all know I can be a bit aggressive in my explanations so I have decided to post an email from quite possibly one of the brightest building scientist / duct designers in North America . His explanation will be better than mine and more understandable . You will clearly see what I was missing in my points and even that I may have presented it wrong based on the type of homes it gets installed This guy has been involved with DOE studies , software design and is the go to guy for most of the really good house advocates . I have designed hydronic stuff along with him in homes where the customer insisted . This is the guy that knows where the fudge is and removes it , by the way , as careful as we are we still are oversizing . So much for the introduction , here it is attached .
Please pay close attention to the statement that when the ratings system was changed the manufacturers gamed the system . Bob said it best , " Lipstick on a Pig " .