Fisrt diary post: house description and tentative flow diagram

[mbeland]

Hi,

This my first diary entry. After a few posts, I thought it might be easier for people to follow my what i want to do if I put my stuff in the diary.

Right now, I am finishing up our house in NB, Canada (cold climate similar to northern Maine, USA)

Basic description: 2 acre (0.8 ha) lot. 28 x 40 ft house (length facing a bit east of true south), 1 full basement insulated with 2 inches styrofoam boards beneath the slab and outside, 2 full stories build of 2 x 6 insulated with glass wool batts and 1 inch foam board, good poly vapor barrier sealed around windows and floors, 1 half story attic (16 x 40 ft) insulated with 18 inches of filled cellulose. Roof sloped 11/12 towards south. Most windows on south side, all windows triple glazing, argon filled, lowe glass. Outside finition all vertical ship lapped locally sawn tamarack. Inside floors oiled tamarack and local slate.

Heating system: radiant water pex tubes beneath floors heated by electric boiler. One circulating pump, 6 zone valves. Wood burning 0 clearance efficient fireplace for back up.

Water heater: regular electric tank with two 220 volts soaking heater elements.

Lighting is in transition from incandescent to cfl, about 1 third replaced.

Next Summer, four years after construction, I will finally be able to install the clothesline.

Someday, I'll convert a gas powered car to electric. Someday, I'll build my own wind turbine. But that's not for tomorrow...

For the near future, my aim is to install home-made solar flat-plate collectors and a big home-made wooden storage tank to heat up water for: space heating, domestic water and accessorily pool heating. Here is my tentative flow diagram:

power point file

Additional details

Total rise from collectors to storage tank will be about 35 ft.

Pool is 21 ft diameter out of ground

I still have to determine:

• area of collectors
  
• length of copper coil heat exchangers
  
• length of dump load heat exchanger
  
• pump power and solar pv panel wattage
  
• how to manage moisture exiting the storage tank
  
• if my actual heating system controller can manage additional pumps, sensors and valves
  
  

Any comments? suggestions? additional questions?

Martin

um you cannot post a power point file as an image on this board just don't work that way .gif or .jpg ect. only i made it a link for you but you mite wanna find a more cross platform file type in the future.
Kurt

[zeusmorg]

 I'm not really understanding your flow on the pool, but why have separate coils for your PEX heat loop and your pool? you should just use the tank water for the PEX loop.(i may be confused by what you're doing there) Used simultaneously I doubt it would keep up with both loads.

 I'm guessing you only want to heat the pool when the house doesn't need heat. Also is there really a need for a tempering valve on the pool loop?

 Sizing would have to be determined by your local solar insolation, and btu's required to heat your house. I believe you'll find information on that at:  

 http://builditsolar.com/ you may find some other ideas that will help there.

 You may also consider a separate system for Domestic Hot Water since at times you'd have a usable heat in your tank for interior heating that would be lower than you could use for DHW. That would reduce the energy usage from your backup heating. Also you'll be using that system year round. Consider, interior heating can be used down to 75 (a stretch) which wouldn't be very useful for DHW. Even temperatures as low as 90F wouldn't be of much help (except for pre-heat) in DHW.

 Some of your arrows seem to be indicating the wrong flow direction.(bottom for back-up tank, between Dc pump for solar panel and exchanger loop.

 I'd also eliminate the float valve for filling your tank and use a manual one and have  a way to know what your water height is.

 Confused by a few other things,also i see a hot line just dumping into tank from DHW circuit? Or is that a pickup line for your PEX? DO NOT EVER mix an anti-freeze solution and DHW. you cannot even switch lines over..so that one is confusing.

 In a nutshell,solar to storage, pex loop uses tank water,DHW would be better off with a separate system (you could use a heat exchanger to add heat to main storage if the DHW has an overabundance)PV for pump power, and determine sizes which without a LOT more info we cannot do for you.

 Oh and looking again, why is there an exchanger loop from the solar panel? Aren't you planning to use an antifreeze mix for the storage, PEX loop, and Solar panel water?  I'm also not seeing a reason for the dump load under the driveway.

 If you used a drainback system for your collectors, you could eliminate the need for anti-freeze, also.

[wooferhound]

I can't view the file on my computer

[scottsAI]

Mbeland,

Good you have done some home work.

You should have asked this before you built. Why?

The 2 inch foam board below slab was not a good investment.

Insulation saving is based on the delta temperature, 50 vs 70 is called never pays pack.

Dry ground is an insulator, why below ground homes were popular.

Side walls as you go up should have been thicker, specially above the frost line and the exposed area should have same R value as outside walls.

Based on your perceived goals my feedback: (I agree with zeusmorg post above).

Tank is too small, heat storage is less than one night at worst case conditions.

No antifreeze in the tank, need double walled heat exchangers for most codes.

Using potable water in the tank a single walled heat exchangers will pass. (as long as you can prove  always potable water).

Nothing wrong with wood tank if it has a liner. Difficult to make water tight.

Since I do not know your numbers estimate based on mine.

My home in Michigan has insulation near yours, 1350sqft.

92% 76KBTU/hr forced air furnace, worst day -23 deg F five days in a row, Furnace run time 23.5hr/day. My basement walls have 1 inch above grade and 4 ft down. Payback was too long to go lower. Broke when completed my house.

Natural gas Tank less hot water is 117kBTU/hr. Unlimited hot water great:-) Can make for nice backup heat. I not setup for it yet.

18,000 gal pool. Heater 140KBTU/hr raise temp 1 deg F per hour.

Very expensive to heat with electric, no wonder your interested in Solar heat!

Largest heat load is the pool, only used for a few months a year...

Have you checked out the links at www.builditsolar.com?

Have fun,

Scott.

[jimjjnn]

Woof... Gotta have crappy MS Works installed to view Power Point pix.

 

[dynaman]

If he is heating that basement 20 degrees warmer than the ground temp he will get a very nice payback vs uninsulated  R14 vs R4  =  1599 btu's per hour  vs 7466 btu's per hour moving through that slab. there is more  exposed surface on that slab than there would be in all the exterior walls of of a 1120 sq ft single story home. This is why this is common practice in energy star homes.

[frackers]

If I had the underfloor heating you had (rather than the electric I'm stuck with) I'd be using my existing 50 square metres of solar on my 60,000 litre swimming pool and put a heat exchanger for a heat pump into it to raise the temperature from the low grade mid winter 5-10 degrees or so to the 30 required for the UFH.

I guess your winters are too cold for that but if you have an equivalent size of insulated tank (maybe doubling as a pool in summer?) then I worked out that I could pull 75kw/hr from it for every 1C drop in water temperature. Mid winter sun would put about 20kw per hour for 4-5 hours a day into it which may balance the heat losses.

The upshot is that it would provide 4-5 days of heating with no sun input before I'd have to worry about ice (worst case conditions here!!).

Since I can't change the heating, I planted 300 trees for the log burner - I start cutting in 2 years :-)

[DanG]

PPT extension viewers....

http://support.microsoft.com/kb/126492 <-- M$ version

http://linuxappfinder.com/package/pptview <--- Linux

[zeusmorg]

 Open Office will also accommodate Power Point files, and it's free.

[mbeland]

Hi zeusmorg,

"I'm not really understanding your flow on the pool, but why have separate coils for your PEX heat loop and your pool? you should just use the tank water for the PEX loop.(i may be confused by what you're doing there) Used simultaneously I doubt it would keep up with both loads."

My plan that maybe was not clear on the diagram is to prevent pool water to go into the storage tank because of corrosion issues. That's why I put a separate heat exchanger coil for the pool. I thought it should be made of pex. The need for the tempering valve is because since the system would be sized for winter heating, I think I will have more than plenty heat in the summer. That is also why I planned for a dump load under the drive way. My roof is very high and I will not go on top to cover part of the collectors in the Summer.

A separate system for domestic hot water and heating may be a good idea. I understand here two separate storage tanks but one single set of collectors that would be directed towards domestic hot water in priority. One may be bigger wooden for heating directly used by the radiant heating loops and the other smaller and pressurized for domestic hot water.

I will check the flow directions and post an improved diagram soon.

The float valve for filling the tank was to make the system as maintenance free as possible. I understand if there is a leak somewhere, I need to be advised so things need not be totally automatic.

I plan to use a heat exchanger loop from the solar panels because I didn't want to have such a big amount of concentrated antifreeze. The amount I would put would be just enough to make it less prompt to grow stuff in the water but not as concentrated as in the solar loops. The other reason is that I was told the collectors prefer to have a pressurized system with no oxygen renewal and I would then need a big pump to be able to push 35 feet of fluid up to the collectors. I understand putting concentrated antifreeze would make the system more efficient though: better heat transfer from collectors to storage tank.

 I didn't think drain back would be adequate to heat space during winter.

Thanks for your comments

Martin

[mbeland]

Thanks for your comments Scott,

You say 2 inch styrofoam is not worth it and above gradee it is not enough. Our soil is rather humid. We cannot assume the slab would have been dry. Above grade is only 6 inches.

You say the tank is too small. I guess it is time for me to actually pickup the calculator and actually calculate load. I think the way I should do this is by analysing my electric bill. Will post again on that. The tank I plan to use is in my mind pretty big (4 x 4 x 8 ft)! That would surely take a fair bit of space in my technical room...

Regarding code and antifreeze, from what I understand, canadian code requires double wall heat exchanger unless there is more pressure in the domestic water line than in the antifreeze side. That is why I assumed it was OK.

Martin

[mbeland]

Hi again Scott,

Here is a plot my electric bill for the last 4 years.

Base usage in the Summer is approx 1000 kwh/mo (a lot of work to be done to lower that uh??)

Peak monthly usage in the Winter is around 4500 kwh/mo but lowered to 3300 kWh/mo with partial wood backup. If I substract the base usage, I get a peak monthly heating load of 3500 kWh/mo or 2300 kWh/mo with wood backup. So I guess, if I planned for 2300 kwh/mo, I would be OK. That would mean an average of 77 kWh/day which is equivalent to 3.2 kW.

Is this ok? where do I go from there? I guess I need to account for cloudy days and inherent variation in solar input...

Martin

[zeusmorg]

 Actually, an antifreeze solution reduces the thermal conductivity of your liquid solution. (check the thermal conductivity of the planned anti-freeze) Depending on type used, this can be significant. That is one of the gains using a drainback system for your solar loop.

 Eliminating exchangers can reduce losses. For instance if you had a heat exchanger on your solar loop, the tank water would not increase as easily as if you used the water directly.

 Heat exchangers should be used to separate Domestic Water from any possible contaminated water. In other words, your pool loop, and your DHW loop. Which could be the same if used at differing times.

 Oh and using PEX for an exchanger loop is not as efficient as copper. Also when I was speaking of your PEX loop I was speaking of your heating system loop(s).

[BigBreaker]

4x4x8 seems big and water retains a lot of heat energy per delta T but space heating requires enormous amounts.  A 100k BTU/Hr furnace is equivalent to 33k watts of electric heating.

You suggest a 128 cubic foot tank.  That's 3.6k liters of water at 4.2kJ per liter per degree C or 15.1 million joules per degree C.  But that is only 15.1k BTU per degree C.  A (small) 100k BTU/Hr heat load will "eat" over six degrees out of that tank every hour.

You need a bigger tank or a phase change material like sodium acetate trihydrate.

[mbeland]

I understand that using the fluid directly is always best for efficiency. Question: if I stick with indirect system with antifreeze in the collectors (I still think it would be best for my climate), is it better to add concentrated antifreeze in the tank (costly considering te volume) and put a stronger pump or add a heat exchanger? I chose to eliminate the heat exchanger for the heating loop instead because it can use water without antifreeze (or with only a minimum amount) without risk.

I didn't get your point about using the same loop for pool and dhw. I need dhw year round. But that gives me the idea of using

About the pool heat exchangers: wouldn't using copper end up having corrosion and pool water contaminating the tank.

Considering all these nice posts, I will have to reconsider my whole system...

Martin

[zeusmorg]

ok, I decided to do a quickie diagram eliminating unneeded things and adding my suggestions.

 To help describe some things, there are two thermal valves to switch from main storage to Domestic Hot Water exchanger storage. A pv panel to supply power for pumps. A tempering valve to insure no scalding water is present at DHW faucets. A heat exchanger for pool,and one for DHW to insure no contaminants enter the DW supply.

 I still prefer drainback for freeze protection , and to make the filling costs cheaper.You'll also notice a pipe(not labeled) between the tanks, this should be slightly above the normal water level, to allow the two tanks to balance their levels..

 I also forgot to add a fill and overflow..oops, and didn't label the house heating circuits pump.

 For simplicity I didn't show any wiring.

 You are obviously mis-reading something my suggestion for using 1 heat exchanger was you COULD switch between the house heat circuit and the pool circuit IF you do not require both at the same time. You NEVER (ever) EVER!!!!! mix ANY water (or switch between pipes that use it)that could possibly contain contaminates with your DW system..PERIOD.

 System usage: PV runs pump when solar insolation is high enough to use the collectors(it's possible to add a mini-maximizer in that circuit). the system drains back (I neglected to add valves for that) emptying the collectors when not in use. Eliminating the need for anti-freeze.

Water is routed to the DHW exchange tank until tank temp is high enough, then switched over to main storage.(or you could have two totally separate systems). Heating is available for pool in summer, and heating the house in winter.

 Sizing solar panels the size of the storage tanks,pumps and the heat exchangers depend on your needs,and I'm not going to engineer that part for you.

[scottsAI]

Open Office is what I use! 5 years now.

Had 12 year old resume written with Word95, tried to open with office2003.

All messed up, 2 hours later still messed up, then tried Open office. Perfect!

[scottsAI]

Mbeland,

French

Eau, soleil, le vent =>Water, sun, wind

As you noticed, many considerations. Knowing your local code requirements is Very important.

Codes are not written for necessarily normal operations, must deal with when things are not working.

Solar heat collectors.

Drain back for cold climates seem to be the best.

Pool must be a new requirement, energy use does not show during the summer.

Tank

Have a porch? Put the tank under it, insulated of course! Www.papercrete.com

2600. l = 686.86gal water is 1BTU per lb. Gal = 8.33 lb.
      
5721. lb or 5721BTU per deg F.
      
      

Lets assume 100 def F temperature change.

Total stored heat is 572,100BTU. One bad evening 8hr its gone!-(

I would target to store one worst case day. Backup after that.

Only been to France in the summer so do not know the winters.

All electric home? Then 1Mwhr/mo includes the hot water not so bad.

My use 764Kwhr this month, with gas.

Have too many computers running (4-5) cost $6 each to run.

Have fun,

Scott.

[mbeland]

Thanks for that nice diagram!

Very good idea to separate the dhw from the main heating storage! I will search the board for drainback valves and sizing calculations.

Martin

[mbeland]

Hi Scott,

In fact "Eau, soleil, le vent" means "Water, sun, wind" but it is a word game because in French in pronounces like "Au soleil levant" meaning in English "to the rising sun"

I am not French from France. I am French speaking from Canada, originally from the province of Québec and now living in Edmundston (90% French speaking), northern New Brunswick. Minus 25 degrees C is about the coldest is usually gets. This week we turned off the electric heat for the Summer and I did a small fire this morning. We had over a meter of snow before it started to melt this winter. We still have over a foot in the woods still (April 24th).

Pool is not heated so far but season is short here.

Our consumption also includes clothes dryer year round. That should change next summer with the new clothesline.

Thanks for the calculations on tank sizing. That would mean at least doubling what I had planned. Do you think it is better to make two 4 x 8 or make a bigger one?

Based on another contributor, I will probably separate dhw from heating, so there could three tanks, the dhw one being smaller though.

Martin

[scottsAI]

Mbeland,

I realized just after I sent it could be Canada, my wife's family is French from Quebec.

Be careful with playing with French words, the Le car did not go over well with the French gov:-)

Edmundston is about 5 deg north of me. -25 C is -13 F.

Michigan rarely goes below 0 F, yet few years ago we had -23 deg F for 5 days, no sun.

Furnace ran 23.5hr, 11pm setback for 6 deg, then ran continuously.

After the second day we never made it to the temperature set point. Ran the burners on the stove for a hour to get it up to temperature. Wife learned just how cold the windows are!

Have you read the stuff over at www.builditsolar.com? Very good ideas for what your doing. Including how to build the tank. Round tanks have less surface area, then square then...

Tank - Needs insulation, one requires less for the same volume of water.

Put a baffle so the new hot water stays in a small area for DHW, excess then flows to rest of the tank.

A year ago I had a nice response on clothes dryer.

http://www.fieldlines.com/story/2007/4/24/14610/4873

Since your's is electric you should be venting into house during the winter.

Without to much work, can reduce heat by 50% was my conclusion.

Pool - solar blankets help!

Above ground?

Quick calculations show 0.5 to 1 inch insulation is very cost effective. (unless have a cheap source of heat). At nigh in the spring and fall it goes below 60 F, with 80 F pool, it cools fast.

My wife wanted 90 F pool, did it for a while, could not do laps was too hot. She hardly used it so backed it down to 80-82F. Bit cold for some, great for me.

I looked at the cost of the pool. Realized its expensive! Only getting two months use for the cost of water and chemicals ($300/yr or $5/day, later got the cost down to $100). Spending the money on a heater more than doubled the season, heating cost was $1/hr with gas. Early spring it was expensive to keep heated, not enough warm days to use it so backed it down to early June through October. Once the kids are in school not much use except on the weekends, so after a while stopped in September. Took pool out once they were in their teens, they could not keep the chemistry right so sold it. I only miss it now and then. Planing on a pool in my next home use it year round. No Cl. Pool cover removal is not fun alone. New pool will have a button to press to remove cover. Chemistry will be totally automated. Nice to be an engineer.

Have fun,

Scott.

[mbeland]

Hi Scott,

Bien le bonjour à votre épouse!

"Be careful with playing with French words, the Le car did not go over well with the French gov:-)" I don't get it... please explain.

Yes I have looked at www.builditsolar.com. That is where I got the idea of a wooden tank. I like your idea of building one single tank with a baffle to separate the DHW storage tank from the main heating tank. However, the problem will be to fit all this in my technical room. From a previous post, I see that I need a bigger tank (at least 2 tanks 4 x 4 x 8 ft) plus the dhw heat storage tank. My technical room is about 12 x 14 ft but one full wall is occupied by the heating system valves and boiler, the second is occupied by heat exchanger, pressure tank and electric breaker box, third one has central vacuum and dhw electric tank. That leaves me a portion of third wall maybe just about 8 ft long and about 6 foot long on fourth wall on the other side of door. It seems like if I want a bigger tank, I need to make it taller than 4 ft high. Considering that space issue, I prefer square tank to round ones. I will have to check code for distance to breaker box.

So far, the pool is the least of my preoccupations. We got it for free except for the labor of removing it. I envision it more like a dump load for summer.

Martin

[scottsAI]

Martin,

70's American Motors (AMC) imported a Renault vehicle they called "le car" for little car.

I remember hearing the French gov did not like this name, if I got this right "The French do not like the butchering of the language like the Americans do"... What can I say I thought it was funny.

Taller tank looks like it will work for you. The weight of the tank is huge, make sure the slab its on can handle the weight without breaking.

I mentioned earlier do you have a porch without a basement under it?

Great place for a large tank. Digging the hole by hand is not too bad. I have done the foundations for a home only took a couple days.

Solar collectors sized by the heat needed by the pool, everything else will be taken care of.

Have fun,

Scott.

[mbeland]

Now I remember the Le car story. I think it was the Renault 5. A very cheap, valuable but very noisy car. Reticence from the French gov won't stop me from playing with words. It's too much fun, especially with two languages (read in French 2 tongues)...

About the slab. Does anyone know how heavy a 4 inch thick slab reinforced with wire mesh can withstand?

I do have a porch but it is only 4 x 8 ft. I doubt it is worth the trouble of digging and making a hole in the basement wall, more difficulty to insulate the tank

If I split the tanks in 2 (within my technical room), I wonder how I could place the inlet and outlet vs heat exchanger coil... Connection between the two tank I guess should be at the bottom.

Martin

[zeusmorg]

 As far as the PSI of your concrete, it depends on several factors, grade of concrete used, and how well the ground underneath was compacted before pouring. The wire mesh reinforcement really makes no difference, that just retains cracks is about all.

 If the slab was properly done, you should have no worries putting a water tank on top. Tap on the concrete to see if you can detect any hollow areas, if any are present then you have some worries.

 Location of a pipe for balancing the water level isn't critical. Water seeks it's own level. Personally, I'd build one large tank with an insulation barrier between them. You create less exterior surface area that way and a lower need for heavy exterior insulation. The top is probably the most critical for insulation, as heat rises. That would save you from any additional heat load in your house in the summer.

 Heat exchangers should be placed near the top for heating applications, (pool, DHW) and at the bottom for solar panels. In other words you want to utilize the hottest part for your heating applications and heat the coolest part. Of course if you go drainback, that is inconsequential, pickup at the bottom, and return at the top.