Do i really need 10 ton's or does my math stink?

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Hello-
Here in vermont i have a 2004's finished ICF home about 4500sqft. Self builder at the time didnt have anough for a gshp install so went with town water and a 100k utica 87% boiler. So me the self builder struggled to get to this time now that i have the equity to take out and install it now. I had run through the vt. effiency folks at the time of building and the house was passed as a 5star"plus" home and i proudly have my plaque on the top of the fridge awaiting front entrance dislplay (6years and counting) ... anyway the paper work that i dug out of the envelope that was up on the fridge says that we were suppose to have 128mmbtu heat load with approx cost of 4500 bucks for heating... also has elec load and cooling but i am interested in heating only. so if i were to use this load calc that was done in mid '06 i think that is about 10fat tons= well i dont have that much equity
i had called a local gshp well driller and had him figure on a 5 ton before i even knew what my load was just so i could figure out what kind of money i was thinking of borrowing. His est. was 10k for well/wiring/pump and controls (not including into the home) so i figured i would have a 25k project based upon using my radiant and hopefully the in place baseboard (installed more footage at time of install expecting low temp water at some point) for about $13k for a 5 ton or so high eff. pump (open loop water back into well)
ok.. so no after seeing the paperwork and what the cost of fuel was in 2006 about $1gal cheaper than now i am wondering if the loads are wrong... ie- paperwork said 4500 heat not including hot water.. well our actual is about 4500 including water at the higher prices of 2010-11 so that means hopefull that the 128mmbtu is not correct? also i am confused because i see heat pumps at go from about 30-70kbtu and wonder would if need 2? definitly out of my budget...
I had called VT to see if we had any tax credits localy and they said no and they were on the fence with geoheat and i should look at solar hot water which has both fed and local incentives?
anyhow this site has been a huge help for me and my wife and now that i have her conviniced to refi i am wondering if i spoke to soon. I have blower door numbers and such and wonder if i should just have someone do a new manual j on the place or such?
thanks all and i hope you can help me make sense of this stuff!

 

I aplaud you for being a self builder, but the manual j heat load calcs is really where you need to step back from your project and call a expert. I would call a hvac guy in your kneck of the woods that is deep into geo and get them to address your project from a fresh perspective, including your load calcs.

This forum is filled with threads about when load calcs go bad and the resulting comfort pain and or monetary pain. The system you are proposing is not for the faint of heart even for an experianced geo installer based on the size of your peoject plus the hydronics.

Just my opinion
YMMV
Eric

 

Whether by actual usage or load calc with blower door test you need a more accurate heat loss average.
Good design does not happen by accident.
j

 

If Joe and Eric are on this

....I'll jump in also.

Since my guess is there is more rock than dirt in Vermont I will skip the loop side of this project.

I will jump in on the delivery side, as I do mostly radiant/hydronic delivery systems.There are several advantages with using water to move heat. My favorite is the increased savings in a radiant delivery system, about 30% according to ASHRAE, followed by the reduced space a pipe carrying BTUH takes up compared to duct work.

Sizing a system requires a bit of work. When I started in this field "bigger was better" and all sorts of similar wing-nut rules of thumb determined what equipment was installed. Now we measure and install just enough capacity.

Here in Ohio we size the equipment to match the cooling load and make up the differance to the heating load with our second cheapest fuel. I did not hear the word cooling in your post starting this thread, so I guess you will not be using the free cooling that come with every heat pump. You might want to think that over now so it could be added later.

You have the raw data to make a good guess on your real heat loss. You know the capacity of your heat emitters at the temperatures your boiler runs the system. Add them up and it gives you the total BTUH capacity. You also have a running total of fuel used to heat the home. Learn the BTUH contained in the fuel and multiply that number by the amount used to get what you have been using. Spiff that number up as an annual average or mean heat loss and compare that to the closest weather history available.

Or....spend $50.00 and buy the DIY heat loss program mentioned at this BB.

Joe makes a good point, that good design is not accidental. You could hire a consultant or as I prefer a mentor to watch over your shoulder to get the most for the funds you will make available while allowing for future expansion.

I have been to VT.

Mark

 

thanks--load check it is

thanks fellas for your help- my understanding was that the stuff marked on the certificate was the product of the heat loss for the effiecny vt thang.. i am glad to be wrong- and i will continue to a contractor that can do this for me; also i might try the 50 dollar program if it looks simple data i/o.
REgarding cooling ; really trying to save on the 4500 dollar propane cost and not really looking for cooling as my wife is a open the windows kinda gal here and it is only about a week in the summer in VT that it gets hot anough to need it; so were used to taking a shower before sleep for the couple of eve;s and tht is that. I will proceed to the next step of looking for qaulified installers which seem hard to find in my area although there are a couple names that i have not tried.
I will post follow up after i get the results on heat loss so you folks can tell me what the best h20/h20 hp i should look at.
thanks again for your time guys!

 

repeating ad infinitum

The "best" w-w HP is the one sold, installed and supported by a local contractor with experience and integrity.

It could be a WF, CM, Hydron, FHP, or any one of several other brands. Most share similar or identical major components.

Installer quality varies much much more than brand quality.

 

125 MMBTU refers usually to the total amount of heat extracted during the year.

Paired with Albany, NY weather data, which should be similar to VT weather data and sized for 97.5% design gives you a -6 degree F design temp and a heatloss of 69,300 BTU/H, which makes a 5 ton heatpump the best match with the lowest operating costs. This is for water-air, with supplement strip heat. Hydronic sizing now needs different consideration, since strip heat needs either integrated in air handlers, the heat elements in the buffer tank, or the system must be sized to fulfill the entire 100% load.

 

Doc

I think that argument has merit. What happens with Vermont Yankee may alter the numbers.

Mark

 

I did not get VT BIN data since I did not know the exact location. I had Albany,NY handy. It should be rather similar.

 

Doc:

I think Albany is close. The KWH rate may rise if they shut down the nuclear plant. They my have a hey day on the mini-hydroelectric plants from Irene,

I will find you next time through Buffalo.

Mark

 

Thanks- looking forward to moving on!

looks like were approved for our refi loan (3.35%yea) and will be moving on this project
found a well driller for 8.50 ft who is about 1.5 cheaper than the closest competitior.
I am happy that you guys were able to do the math on the amount of btu heating that the
efffeincy vermont guy had figured.. i was hoping to go about 5ton and wondered what your thoughts were to the reply regarding going hydronic apposed to air which i was hoping to do but wondered if these systems ussually require more or less tonnage capacity. I DO plan to still get a manual j done from a proff. although i am having a time trying to find someone qualified in my area. also had a question regarding how to put the water back into the standing coulumn.. does it just get dumped back into the top of the well? also regardnng this i wondered if anyone was familar with using outdoor furnace type insulated tubing to bring the water into the home? we are about 2 feet above bed rock here in VT and i will have to dig like a son0fagun to get any deeper so the insulated pvc pipe might need to be used. another thing that i cant find anyone touching on was slab cooling: doest it work to pump cool water into the slab for cooling in the summer?
thanks guys ! as this project continues i plan on full series of pics and news!
thanks
tony

 

Tony

For your Manual J, you might look to speak with a local energy auditor. You'd get the benefit of a blower door test as well.

Slab cooling: the dew point can get in the way of that.

PM me, I am in Albany NY and might be able to assist you.

Where in VT are you?

Zach

 

A manual J in a retrofit house will be a guesstimate at best, your last years usage is real data.
The $4500 you paid at last years prices match the 69000 btu/h heatloss, actually a bit less.

They match 2134 gallons of propane with an 84% efficient boiler.

The only thing now making things complex are inefficient baseboard, you don't want to run your heatpump at high water temps all the time.

Might be worth pulling air ducts through the building, or upgrading the excising baseboards with high efficiency or regular radiators.

It depends on what you prefer. If you stick with baseboards requiring high supply temperatures, an outdoor reset is a must.

 

baseboard and such

regarding the low temp baseboard idea; this is the way i would prefer to go.. can you send a link or manufacture of such units?
when you did these calculations and said based on the actual fuel numbers are you thinking that my tonage is around what? just want to think that i am still in the 5- 6 ton range. my house is a quite open floor plan design with high ceilings (11ft everywhere upstairs (2000sqft) 9 downstairs half belowgrade (kinda like a raised ranch) i will find some pics to put on here seeing that you guys may be interested.
and what about the insulated pipe to run to-from the well?

 

Smith Environmental Hydronic Baseboards. Heating Edge Hydronic Baseboard. Hydronic Heating Systems - Radiant Heating System, Solar Heating, Geothermal Heating

If you want to stay with radiant baseboard you don't have strip heat to use for supplement. But you can use the 5000 W electric heat element as supplement heat for the coldest days.

Simply use the heatpump as first stage, and the electric heat element as second stage, but use a simple boiler control (e.g. Tekmark 150) to not allow it to come on above a certain outdoor temp, for example 5 or 10 degrees.
Keep in mind that the BTU rating of the heat pump is for 32 degree EWT, and 104 degree ELT. Running it at 120-125 degree supply temperature will decrease the capacity of the heatpump (and the efficiency).

Yes, the 5 ton W-W Climatemaster or Hydron would do the job, combined with the electric heat element in the buffer tank for supplement heat, based on the data you have givenus so far.

May be you could post the efficiency of your current boiler, the actual gallons used last year and your exact location, then we could better zoom in on the numbers.

I don't see much issue of the header trench being only at 2 feet. Should be below the actual frost line, and you have the pipes insulated and filled with antifreeze.

 

more heating info

currently have a 125k utica boiler 87% stamp on it. Propane hot water. Last year we used approx. 1600 gallons of propane all year.. this is for hotwater/heating only. we have a small pellet stove in one room and we burned about 40 bags of fuel for the year. we live in 05458 east shore north road. Does the heat strip your refering to just supply DHW extra heat- so we would have the pump heat a storage tank and then pump it into a DHW with the supp. unit?
as far as the trenching goes i was planning using scw type so there will actually be water in those pipes.. were you thinking that i was doing a closed sys? thanks for your thoughts
-tony

 

Uhoh that changes your usage.

 

Geothermal radiant works best when designed for low temperature water (120 degrees max). Best radiant designs occur when loads are known for each room. Best radiant design uses primary/ secondary pumping with outdoor reset control. If you're thinking about water to water geo heatpump, solve the radiant design first and then work out the geo design. I'm not a pro but I have a wet head and a some experience . Best of luck with everything. Hydronic (floors) are great but the install cost is high. Baseboards probubly won't be large enough to deliver enough btu's with the low temp water of a water to water system.
Inside my house I installed a woodstove with a stainless steel coil. The woodstove can heat the livingroom (air) while the hot water produced can heat the bedroom without using the water to water heatpump or the water to air heatpump. Radiant tonnage does not equal air system tonnage when sizing. The reason is that the heat losses are different with different systems. For a retrofit the radiant design with geothermal won't be easy or cheap. You might be able to reduce the load with energy efficiency upgrades (more insulation.. better windows) enabling lower tonnage and a smaller system.

 

40 bags at 65% efficiency are about 200 gallon of propane in a 84% efficient boiler, so you are using about 1800 gallons of propane. Matched with Burlington International Airport, Vermont, weather data you are now looking at 54000 btu/h heatloss at -6F design temp. That includes you domestic hot water, I don't know what your usage there is. Usually you are looking at least 20%.

Very good for your size house. Looks like a 4 ton if you are going with forced air, if you are using a DSH, 3 ton might also pushing it, but my gut would like to see a more responsive system, with a 5300 sqf house. If radiant, your efficiency will go down if you are going with your radiators. 5 ton if you use hydronic. 90-100 F supply temp sounds unrealistically low, even if you have such an efficient house.

SCW helps since it raises your average incoming water temp, increasing your efficiency.

 

optimistic?

well i am .. that last reply and thanks to all you number crunchers .. i was hoping and planning a 500ft well.. so i am very happy to hear that 4-5 ton is in the range there.
i have called now 3 people that have not returned my calls... one is from the guy that wrote this interesting article
http://www.efficiencyvermont.com/pages/BBBD2008/Ground Source Heat Pumps_Shapiro.pdf

its a pretty neat article but the company who did the design (in the tech drawings) has not returned two calls...
oh well-looks like from the help of the experts on this site and some expierenced contractors i might be able to get it done by self subcontracting.

I was just told today by someone that we could use a on top of ground or mound type gshp system (never heard of myself but guy was atimate about it) anyway that would be great here where i am because we only have the ability to dig about 1.5ft without hitting hard shale/bedrock.. anybody heard of that?
also wondered about using propane as the suppliment heat for the dhw or do you all recommend strip heaters or elements in the hotwater tank..
thanks guys
might try to get pics of my current stuff this w.e. to show everyone something seeing you are all giving me some of your time!