Roooooomie,

If the heat pump's NORMAL MIN EWT is 32F and it is YOUR expectation to have at least that, then you discuss your concern with your trusted contractor and include it in your contract. If the contractor believes your expectation is
unfounded, he or she needs to convince you.

No one wants leaky ducts, noisy operation, high electric bills, lockouts, over / under capacity, uninsulated desuperheater plumbing ... They all fall under PROPER INSTALLATION of the system, and "proper" is often implicit.

The least having a "min EWT under normal conditions" clause in your contract will do is that: it clearly conveys your concern about loop performance to the contractor.

I would have been upset if my EWT had fallen below 32 F during this harsh winter.


Regards, Masoud

Bob,
I agree that this is a good discussion if not to the 32* clause. Performance is important in the decision to spend tens of thousands of dollars on a system. Performance however is a cumulative thing that is not represented by one measurement. I have found my operating cost calculator to be extremely conservative and therefore my customers have enjoyed pleasant suprises in an especially harsh winter. The real measurement that pleases people is the electric bill. The EWT is a factor, but not the only one in that final analysis.
The point that I am (again inarticulately) trying to make, is that a single measurement is not a good indicator of overall performance. In dealing with weather, is the temperature the only factor? Of course not. We deal with wind chills and heat indexes because more than one measurment affects comfort.
I've said it before and some here might criticize me for it, but if I'm responsible for performance then I will design the system. If I have a customer who wishes to design the system, then they assume responsibility for performance.
Customers who insist on oversized units but do not wish to modify duct systems, for instance, may have an experience that is less than desired. Many factors size a system, to focus on one is folly.
Shelley,
Your idea is great! With Bill's recent experience on changing a fan coil he had a check list and a notion that if most of the criteria were met- his contractor did a good job. Are there things I would do differently, sure, but tradesman are creatures of habit like every one else. If we suggest a check list with a target of 7 or 8 out of 10, it might be a great resource for shoppers.
To the 32* issue again; dipping below freezing is not indicative of poor performance in all cases. I melted down recently on this site because of a notion that aux. coils shouldn't be used and loops shouldn't frost. Everything is a trade. If you don't want to pay to much for the system and you don't want to pay to much to operate the system, there are balance points and trade-offs.
I will challange anyone here again to explain why the designers of these systems permit operation at 15* if EWT shouldn't go below 32. 32* is an important number in open loop systems, but in closed, not so much. Ask folks in TX (paging Bill) if he would care about a 32* clause at all....it's all relative.
In closing, I don't contribute here to design systems in lieu of your installers. There are geographical concerns in climate, material, soil, equipment availability etc. That's why customer referrals trump all our advice. If your contractor has made all his other customers happy, you probably will be too.
J

(Answering Joe's 'page')

This has been a good discussion.  I've been keeping up with the excellent comments.

I'm in the minority, not aligned with the general consensus that HVAC contractors should not offer some kind of performance guarantee.  Instead, I see it as an incredible income opportunity for HVAC contractors, and, an opportunity to separate from the competition when in a cut throat competitive HVAC market like what exists here in the Dallas area.

But, I believe it would take a lot of skills in the 3 fundametal areas: sizing/selection of equipment, designing/installing the loop field, and solid air distribution skills.  And it would require a reliable measurement system such as a WEL unit.

Yes, I don't care about my EWT right now.  Producing heat right now in the Dallas climate is an after thought.  But how warm my EWT gets is a big deal.  It gets blistering hot here in the summer, and 90+ degree EWT water doesn't make for a very efficient system.

For me, individually, the most important thing is the utility bill.  But a close second is comfort.  The reverse is not true, though.  I would want to hire an HVAC professional who is capable of outlining my comfort options, tells me what my utility costs will be, and tells me what the initial capital outlay will be for the various alternatives.

I'm particularly thankful that I have an EWT chart like what's below.  I can easily see how well my vertical loop is performing, with EWT ranging from 63 to 83 degrees on a full year basis.  This chart, plus my other charts, pretty much tells me consistently what the health of my HVAC system is.  The incremental investment I made into putting in a WEL unit has been immensely useful, informative, and satisfying. 

Thanks for the opportunity to comment.

Best regards,

Bill

(P.S., yes, having the checklist to understand what to expect when having an evap coil replaced was very helpful, and much appreciated.)

 

...and performance is assured (with disclaimers), where comfort and savings are concerned, not each individual operating press. or temp. Bill, your concern that the EWT doesn't get too high illustrates my point that a 32* EWT clause is arbitrary and regional and not likely to excite interest from many experienced contractors. Those who do promise it should get a written guarantee from the homeowner that aux. coil will not be disabled.
You could just as easily ask that operating pressure never exceed "X" or leaving water temperature never be below 25*, and if you find a contractor foolish enough to promise it hire him (though I suggest you check his references carefully as he may be new to this game). I can't even guarantee EWT on an open loop system (though I know how low LWT will go before lock-out).
With plenty of carpet baggers on their way to cash in on the new tax credit, beware of those that predict weather...
How many active contractors out there currently offer an EWT-LWT-Superheat-Sub cool-EAT to LAT delta T-GPM-minimum C.O.P- etc. warranties? All are important to performance, yet if most are where we want them the result is good.
I'd really like to know which of you give these guarantees?

I have never been asked for any lkind of performance guarantee. I give potential customers a list of 20 or so references and say call as many as you like.

This seems to satisfy them.

(Incidently most of the COP's advertised are based higher EWT's).

As an aspiring contractor with few to no references to call upon (how do you get around that one?), I would seriously consider a performance guarantee. As Joe pointed out, EWT is probably not the best metric to use because it is subject to so many variables (and to manipulation by the HO or contractor). Instead I would focus on 2 numbers:

 

1. The ability of the system (including any designed aux heat) to keep the house at x degrees on a y degree day.  Disclaimers here would have to include modifications to the house, leaving the windows open all day, etc. This is pretty fundamental to most any heating system.

 

2. SEASONAL average COP or power use for a given number of degree days. This would require more explanation/disclaimers and some level of datalogging, but is also fundamental since most people put in these systems to save money. Without this #1 is meaningless since a system could just run aux heat all the time. Obviously there would have to be some safety factor, but I feel like this should not be a problem for a good installer. You’d probably need a disclaimer for a mini-ice age or whatever, but even though there are cold months here and there over the course of a season things tend to even out.

 

These place added risk and responsibility on the installer but in my opinion also offer some protection since the HO would have the system design performance in writing and would be better educated about what to expect. I think the only real risk would be if you came across a customer that was outright trying to scam you by fudging data etc. Hopefully these would be few and far between.

 

As a customer I would want a guarantee like this (I would be willing to pay a premium for it) and as a contractor I would have no problem offering it.

If you are a longtime contractor but new to geo, you still have plenty of references to offer. If you are new to both, find a retired contractor or distributer to partner with until you have a resume' built. If you can't offer either then you shouldn't be compared with an experienced guy in your area.
You would then have to sell friends and family members first or work for another contractor.
Curiously we have cases in court in MI right now due to high system operating cost (not geo that I'm aware of). Every system we sell has average operating cost calculations with them and apparently that's already actionable.
J

IF, big if,  I  was going to offer a guarantee,  it would be something like this:

The average annual  heating degree days  for you area are  ###
You heating bill will not exceed  $$$$,  if the HDD does not exceed the average. 

Of course there would  have to be disclaimers for tstat set point, windows being left open,  paying the neighbors to make sure that the windows are not left open  etc and etc.

Thanks for the continued thought provoking 'conversation.'

I agree it doesn't make sense for an HVAC professional to guarantee an individual metric to perform better than manufacturer rating.  I.e., it's clear water-to-air/water GSHPs are designed to function quite well with EWT < 32 °F.  A guarentee that EWT won't get colder strikes me as quite arbitrary.  The same holds true for EWT > 90°.

I'm more aligned with the example Dewayne offers above.  Most customers understand 'what it costs.'  Far less customers understand EWT, or even care to understand it.

Overall I believe there's a lot of opportunity (increased revenues and enhanced reputation) for the adventurous and highly skilled HVAC professional who can figure out how to offer performance guarantees of some kind, without a 'novel length' amout of disclaimers, that thus end up being win-win arrangements.

Fundamental to the whole discussion is having a monitoring system that can be counted on to be reliable and accurate, such as a WEL unit.  If I was an HVAC professional I'd be marketing this as an 'add-on,' and charging appropriately for it (i.e. with proper margin).

I think there are 2 key metrics that well describe the health of an HVAC system: Heat of Extraction/Rejection (loop field's performance) and Heating/Cooling Capacity (air heating/cooling performance.  If something's wrong with any of the many metrics, the problem's going to probably show up as an impact to either/both of these metrics.

HE/HR is easy to measure/record with a WEL unit when there's only one GSHP unit per loop field.  See below for an example with my system.  HC is still within the WEL's capabilities, but with a few more qualifications (one GSHP unit/loop field, ECM motor only, no zoning).  Cooling Capacity is tough because a key portion is Latent cooling, requiring installation of humidity sensors and advanced computational logic to determine Wet Bulb values.

(And COP/EER real time measurements, that would be accurate enough to be part of a guarantee, are very difficult to obtain with a WEL unit.)

In summary, I think the power of having some kind of performance monitor chart for customers, like the second chart shown below for my system, can be very powerful and lucrative for the creative and well-skilled HVAC professional who's operating in a highly competitive market.  (In my case I'm down 43% per month compared to where I was before installing GSHP HVAC and putting in a WEL.  And this is net of electricy rate hikes and wild natural gas price increases/decreases.)

Thanks once again for the opportunity to contribute.

Best regards,

Bill

Bill,
What guarantees sold you your system?
I ask not to antogonize, but you have become sharper about geo than much of my competition along the way.
So tell us what clenched the deal for you?
j

I completely agree with Joe that a min EWT temp of 32 degrees is purely arbitrary in this discussion, as it was suggested in the initial post. However, in cold climate, a specific min EWT is a significant factor in determination of the loop size, system capacity, and overall cost of installation and operation, thus it should be transparent to the customer - similar to the building's heating and cooling loads, balance points, desired temp setpoints, expected operation cost, maintenance...

Climatemaster specifies its normal operating min EWT = 30 F for heating.

When I had my GSHP installed last fall, I did not ask for a guaranteed min EWT from my contractor. I asked: Will I have enough loop? A yes was followed by a handshake and a smile. My EWT went down to 36 this winter and its already up a degree. Craig, I am thankful.

Regards, Masoud

The short answers:

... Didn't receive any guarantees - closet thing was my research that geothermal HVAC should have a much lower monthly operating cost than convential A/C.  (see chart above to see we were spending over $900 / month for cooling in a blistering 2006 summer)

... Two things clenched the deal:

1. Recommendation from WaterFurnace Texas Territory Manager to proceed with a particular HVAC professional.

2. Price proposal from HVAC professional seemed reasonable since it included equipment, drilling, and new air duct distribution system.


I got fortunate things worked out.  It was fortunate that the HVAC professional:

a.) changed to another drilling firm when originally planned firm kept not showing up - replacement drilling firm was highly skilled commercial firm.

2.) used 300 ft/ton bore hole length rule-of-thumb for loop design.

3.) asked assistance from long experienced geothermal professional to fuse HDPE pipe.

To this day I don't know if Man J, S, and D analysis were done.  I couldn't insist without risk that HVAC professional would therefore decline to do the job.  And WF TM didn't have another HVAC installer to recommend without going all the way out to Waco, TX (over 100 miles).

Best regards,

Bill

Question:

Any one actually designing loop fields for less than 30 degree F? It's interesting to see how much more pipe is required for 35-40 degree EWT design. It seems that 30 degree EWT is a good parameter to use for close loops. You have a safety margin for things beyond your control.

Bob

Default temp on my (CM) design software is 30*-95*, so you make a good point Bob, I don't design for 25*, but I also don't design for -20* (though I know we have been there, so I ensure adequate aux. coil).
Bill,
Sounds like you came out okay, but I had the other end experience where a distributer suggested another contractor over me to a customer i had already been communicating with. His motivation was to keep his number one seller happy; not customer satisfaction. That product and that dealer are quite possibly headed for serious trouble (dealer is a fan of the thumbulator load designer).
Folks, you want end consumer refrences. Ask for one or two jobs that didn't go perfectly and find out how your contractor behaves when things go wrong. That will show you the character of the firm. Insist on a Manual J calculation, and some sort of operating cost projection. Don't ask anyone to predict the weather.
These are things that will get you a good contractor.
The arbitrary EWT guaruntee will not.
J

My observation is that If you're a WaterFurnace installing HVAC professional in Texas, you'll be professionally treated by the WF Texas Territory Manager.  Further, based on directly observing a number of situations here locally, it's my conclusion that WF is pushing hard on sales of Envision model units and is doing it with a model that's holding up well with little break down so far, and, is emphasizing carefulness in HVAC professional dealership.

Best regards,

Bill

I wish I could say my area rep was so helpful. I have been after him for more than a week to contact a possible installer I like who has been using another brand of GHP for a dozen years, successfully. It took me a another 4-5 days just to get him to respond to my original two phone messages and two emails. I don't care how busy someone is, it's bad business not to return phone calls or follow up when you say you will. I am not impressed by WF so far and am concerned that if anything doesn't work out, the rep will not be there for me.

Sunnyflies:

It could be that the WF rep doesn't want to contact an HVAC professional who has been successfully installing a competitor's product for as you say a dozen years.  Although you could argue that professional courtesy would dictate that if this is the case the WF rept could simply be state as such.

My observation is that if you want WF equipment you'll be limited to working with an already authorized/supported WF HVAC professional.  If instead you want WF equipment but with someone else, it probably won't happen.  I.e., your only option ends up being to go with some other equipment manufacturer and HVAC professional.

Also, I don't think the rep is in business to directly engage with the end customer.  If something goes wrong with the end customer's equipment, the rep is going to expect the end customer to work with an authorized/supported HVAC professional.

In fact, at least in the case of WF, if you examine the warranties carefully, you'll see that the warranties are actually between the authorized/supported HVAC professional and WF itself.  Interestly, the end customer doesn't have opportunity to make a warranty claim direct to WF.  I believe this is the case with other major brands too - I don't think this is anything unique to WF.

Best regards,

Bill

Bill,
the story provided was not about WF (or for that matter water anything). I'm not a WF dealer but have suggested that the dealers in my area do a good job. Seems like your experience has been the same. Biggest WF in my area has been dropped however and I'm starting to see customer impact. Your experience sounds positive however and it wasn't due to the installing contractor (as I recall) which offers high marks to the brand.
Sunny,
I can't speak for everybody here but my feeling is that most systems are good, so if local response is poor from one brand, call another.
Not every area is well represented by every brand. Keep us posted.
J

We install DX which has much different criteria when it comes to system performance.  We monitor our clients systems very closely for electical usage - which tells us how the systems are performing - we believe in real-world data.  Lab performance doesn't cut it.  

From trial and error over time we know the optimum earth tap length (for our compressor assemblies) is appx. 70 feet and each will produce 6,000 BTU/H.   That said, system design and sizing is critical.  Covering the entire thermal envelope with the proper BTU's, but screwing up air distribution is just as bad as undersizing the system.   Adding additional tonnage because the client wants to "crank up the system" or cover him/herself for -10 F when that happens for 15 hours each heating season is foolish and counterproductive.  We're talking Energy Management - and that means sizing the system for the expected conditions.

Hope this helps,

Paul
Total Green