Solar piping diagram

Darin Cook_5

In my opinion and from all of the information that I have studied - domestic hot water preheating is by far the best bang for the buck with solar thermal. But, depending on the construction of the home, what their fuel options are, and if it is utilizing low temperature radiant heat it is still very possible to significantly offset the homeowners fuel bills especially in the shoulder seasons.

I have a Buderus solar hw system that I am installing this coming week. What I am choosing to do with the 80 gallon dual coil indirect is pipe both the coils together in series. I will enter the top coil first and then enter the lower coil for maximum transfer surface area. I will pipe my incoming cold water supply into the solar storage tank come out of the hot and into the cold water tapping on the LT 160 indirect. The boiler depending on the time of year should have very little run time (small to zero in temperature rise to overcome) with the indirect. The LT tank will have a thermostatic valve installed to control the outlet temps to the plumbing fixtures. The beauty of the system is that the boiler is the new G125BE (89+ afue oil) with the 2107 Logamatic that will run the solar package with the FM solar card. It will be a very efficient system for these folks! With #2 oil at $4.39 a gallon here, the tax credits on the solar, the solar hw system should be generating "free" hot water in a couple of years. Well worth the investment for this household!








Darin

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Mike Dunn

Any Thoughts...

would be great on the following solar piping schematic. It is for my home. The boiler is a GB-142 and the horizantal solar storage tank is a buderus 79 gallon indirect. The solar differental controller should keep the solar DHW tank hot first then switch over to the storage tank if there are left over btu's. The 3 way valve will also be run of a differential controller. The primary loop will always be 140 deg for the air handler coil.

Fire away please.

Wayco Wayne_2

I am

having a little trouble following the solar circuits from the panels through the tanks. What does the Calleffi control do? does it have a circulator in it? Also how many panels do you have? Enough for domestic hot water and radiant floor heating? WW

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hot_rod

good

what temperature do you need for the fancoil? will it run off the boiler reset?

Do you have enough panel square footage to make it worth adding the additional storage and heating interface?

Check the solar radiation available charts for your area to see how much you might harvest on a cold winter day in your area with the array you have in mind.

I prefer the dual tank method for SDHW. It seems to present more solar "harvest-ability" by presenting a cold tank to the solar every morning.

Either tank will work but dual coil tanks are always hot on the top half from the boiler coil.

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Tim P._2

BTU's

I'm contemplating solar for DHW + radiant as well.

From what I have researched, I don't know that adding a storage tank will be of much benefit.

If your house has a 100k BTU/hour load. You have 80 gallons of storage at 180 degrees. You require 100 degree water for your radiant loops. Therefore you have 80 gallons with 80 degrees to lose. At 8.34 BTU/gallon/degree that's 53,376 BTU available.

So, you have 1/2 hr of heat available after solar collection stops.

Now figure how much BTU your panels collect (usually measured per day) and you can figure out how you would fair during the day. The storage tank won't be much use during the day, unless your panels are putting out more BTU per hour than the house needs, or you are diverting those BTU to storage rather than immediate use.

In my own situation I found the only viable solution was a lot of storage (thinking 1000 gal) and a large evacuated tube array.

Tim

Mike Dunn

Solar piping diagram

The caleffi controller will keep both the tanks hot via a differential controller. The pump is built into the control station. I am using 3 panels. I doubt its enough for high quality space heating but I am more or less experimenting to what I can get out of it and will it justify the extra dollars spent on a tank and extra controls.

hot_rod

Doubtful

that 3 panels will add much in a cold winter condition. Go to the www.srcc.com website and look up your panel to see the output.

Here is a 4X8 typical flat panel collector. At 90 degree look at the output on sunny and mildly cloudly days. It may not pay to chase down 2- 20 thousand BTUs generated per DAY by those panels.

But if you like to mess with solar and could add additional panels, go for it. That Caleffi controller has a lot of features to move and keep track of solar harvest.

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Mike Dunn

hot rod response

The fan coil is at 140*. Can I reset the boiler for the fan coil water? I was thinking I would set the boiler at 140* and get what effieciency I could from that. If the boiler resets the fan coil water cooler won't the discharge cool down and thus feel cooler as it is blowing into the house? I am short panels for peak solar heating needs but this is an experiment to see what I can get. On an average winter day I expect to collect around 42,000 btu's per day. The heat loss on my house at design(-15) is around 60,000 btuh. I will be installing a btu meter on the boiler side so I can compare usage between the boiler and solar.

Wayco Wayne_2

I've been crunching numbers.

Boy is the payback painful on Solar. When you need it most it ain't there. You can spend $7000 and save 50 bucks a month. Whoopie! Actually I exagerate. If I install a system to provide hot water and assist my radiant floor it will help more in the shoulder seasons when the transmission of the panels rise and the heat loss of the house declines. If I do it it will be for the fun of it, not because it makes back a lot of money. WW

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Mike Dunn

Hot Rod, When you

say DAY is that amount generated in a 24 hour day or a 4 hour day, like from 10am to 2pm?

hot_rod

the solar window

depends on your location, an example from Caleffi I-dronics # 3, page 4

40 degree N latitude with the collector at a 40 degree pitch
8:30- 3:30 winter,
7:30- 4:30 summertime

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hot_rod

A good, solid plan, Darin

how much panel square footage?

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Darin Cook_5

HR

It is a two panel system ( two adults in house )with about 48 square feet of collector surface. It should offset the homeowners oil bill nicely.
Are you going to be doing any training in the Northeast ( Upstate New York )? I hope life is treating you well at Caleffi.






Darin

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Dave Yates (GrandPAH)_2

WW

Last year, I calculate we harvested a bit more than 29,000 gallons of liquid sunshine! I recently purchased an additional 20-vac tubes to be added to the 30 currently in use. Before I add them, I need to build in some thermal storage for use with the hydronic radiant system because we'll be at 100% domestic hot water plus from solar.

Can't decide if I want tanks or if constructing a storage tank (adjacent to my mechanical room, the storage area is block walled on three sides - might be suitable for lining & filling) makes better $en$e.

Plans for adding PV are coming along nicely too(G).

PA will shortly have a 2% fixed-rate loan available for alt energy systems - making PV an affordable and attractive add-on. Net metering is now in place. Although Met-Ed only gives back the "production" costs (so I've been told - working at trying to confirm that or get the actual rate Met-Ed will pay - a more difficult task than it should be)- a little over 5-cents per kWh - our local legislator had a bug put in his ear to think about this: If the producer of PV-power being pumped into the grid could have those PV-kWh's put into a Green Energy "bank" and folks on the grid were interested in purchasing green power, then let Met-Ed sell it at the current full-rate, but pass through the "production" rate to the PV-power-producer. We currently pay just a bit more than 10-cents with a 5.9-cent "production" rate for each kWh. That way, the PV owner would receive 11.8-cents for each kWh pumped into the grid while paying about 10-cents per kWh for power received from the grid and folks who want to feel good by purchasing green power could do so for the same kWh rate they're currently (no pun intended) paying!

hot_rod

Hi Darin

I hope to make it up your way. Roger Corrente is our regional Caleffi person in that area. roger.corrente@caleffi.com . He is looking for locations and dates. If you have a dealer or wholesaler you like send the info our way. We try to do a bunch in one area to take advantage of the travel time and costs.

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J Prisby_2

Training Interest

Hot Rod,

When you get a moment, I would love to see your MI Training Schedule, as well as anything you have coming up at the Factory in Milwaukee. Our paths will cross soon, I am sure. Being located in Chicago and covering the Midwest Territory, I am open and close enough for something last minute. How's MO in the Summer, it's been a long time since I have been in your neck of the woods. I'll shoot you an email regarding what I have going on.

Jim Prisby

Unknown

Mike,

My experience with the Gb is that at 140 you don't get a lot of condensation in the combustion chamber, lots in the vent line though.

I think your schematic has a few two many circs. simplicity has it's merits, will the heating component justify the expense? If you end up with any meaningful shoulder season heating capacity this implies a dhw over capacity in the summer, what will you do with this extra heat?

Perhaps you could dedicate some of the basement radiant loops for solar. You could probably soak up all of the available solar btus in the slab alone, I agree that the solar heating component does not necessarily justify storage.

Seems to me that you have to many layers of hydraulic separation, all these circs. cost money to run. Why use the Hydrolink when you could just tap directly into your secondary loop via additional T's and avoid an additional circ. Or loose the Budarus T's and pipe directly to the Hydrolink. I don't love that Budarus forces their P/S arrangement on the N.A market. In the Netherlands this boiler comes with a circ. in the bioler inclosure, and a diverting valve for DHW (notice the unions where the circ. should be)

Consider over-sizing the coils in the air handlers so that they can run at temperatures closer to the joist trak zones. If your boiler is forced to operate 20 degrees hotter than the radiant requires on account of the air handler, you will not be getting the best possible performance from your boiler. Getting the best performance from your condensing boiler and reducing your pumping costs may represent a better ROI than the solar space heating features you are considering.

Metro Man

storage

Yo Parnasses (sp) boy! PA hot enough yet?

I would go with a central storage tank and pull off for all the loads. Keeps design and plumbing simple.

Let me know what size and will $$ a stainless steel tank for you. I'll even send some Coors and you can send back the Yuengling.

Metro Man

Mike Dunn

Revised my piping layout

Thanks Scott for the comments. I have revised the drawing to reduce the amount of pumps and eliminate the dedicated solar storage tank.

Now the horizontal tank will be an indirect off the boiler fed by the solar tank.

I will feed the primary some solar btu's when available through the upper coil of the tank. When it's not available then the boiler will take over.

Fire away...please

Dave Yates (GrandPAH)_11

D'OH! Missed the reply

You're on for the beer-swap! Make that a Fat Tire. I'm limited by the doorways, so any tank would have to be a max width of 30".

hot_rod

could you

have the solar cover the DHW tank first, then the dual coil tank. I'm not sure of the array size. But pick the easy, year around load directly, and first, the heating load after the DHW is satisfied..

Then the dump could be the dual tank in the summer, depending on array to tank size, of course. No reason that tank couldn't run up to 200F or so. Unless the manufacturer doesn't allow it.

Also you could feed the HydroLink right from the boiler without the P/S loop around the boiler. Saves an air purger also.

The Caleffi Solar Pump station has an intergral air purger, I'll bet the Viessmann brand might also.

If you have a copy of Caleffi Idronics 3 page 26 and 27 are real close to what you are trying to do. Although it uses only one dual coil tank and the boiler does DHW via top coil.

With enough boiler HP you should be able to generate plenty of DHW this way, and skip the second indirect.. My Knight 80 will run a shower heat non stop piped like this, around 1.85- 2 gpm.

Idronics 3 is a free download at www.caleffi.com if you don't have a hard copy. If you need or want a copy let me know.

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