Spitballing solar piping ideas

Wayco Wayne_2

I must state that the HX in the top of the storage tank isolates the potable from the heating circuit. Also the circulator that moves hot water to the storage tank from the Polaris would be on a 2nd stage operation and wouldn't operate unless the storage tank is not hot enough. I was even thinking of having a timer to lock it out during the day, but that would not take into account overcast or stormy days when there would not be enough solar to heat the house. Perhaps an end switch on the differetial controller would be a better lock out control. Also you got me thinking about the dip tube of the storage tank. If I cut it so I was only heating the top of the storage tank that would leave the bottom cold enough for the solar if it wanted to work. Hmmmmm. WW

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Wayco Wayne_2

This is for my house

I have an existing Polaris that I will be adding solar hot water too. I have a hydro HW coil backing up my heat pump.(Design temp 140) I have a snow melt, ( I seldom use it since we don't get much snow.) I also have a radiant floor loop that does my entire 1st floor. The Polaris has a side take off I can use to recycle hot water when there is a call for heat. Let me know what you think. WW

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Metro Man

Heat Exch.

I would not heat the storage tank to heat loads from the polaris. How about a heat exchanger off pot. recirc from polaris to loads?

You may want to consider a 3-way valve to isolate solar tank from loop when in gas heating mode. This will prevent the returns from loads heating solar tank.

Isolating solar tanks from any gas or electric heat is what we always do. Let the solar heat the storage tank to whatever it can whenever it can.

Metro Man

Wayco Wayne_2

Thanks for your input

Do you have any piping pictures to show me what you mean? WW

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Metro Man

no pics but

Maybe I can explain.

I would install a HE to the left of storage tank in line with the feed to loads. Tie the pot heat recirc line (purple) to HE and do not run it to cold of storage. T return into "pot from storage tank". You may want to put a spring chk on hot out of storage tank.

The zoned returns of the 3 loads then should be plumbed through a 3 way zone valve so you bypass the storage tank HE when heated by polaris.

3-way could be controlled by a set point temp controller. Herein lies your problem. You have to pick a temp that you are allowing heat from the storage tank to heat all three zones. If the radiant and fan coil are the same, no problem, the snow melt will be fine.

There are more ways to do this but the main thing is to NOT heat the solar storage tank with the polaris.

Good Luck...

Metro Man

Wayco Wayne_2

Thanks for the input

I hear you about isolating the storage tank. At the moment I don't totally agree with you. Please forgive me. I may come around given time to think it through. I woke up this morning worrying about the upper HX in the storage tank having enough capacity at 140 degrees from the Polaris, to deliver the 56,000 btuh I need for my house, so I added a mod con boiler and left the Polaris for back up hot water. I like this config since I can ride the boiler outdoor re-set if the storage tank doesnt have hot enough water. Also I can modulate in what extra capacity I need. (Gawd, I love to draw with this program. What fun!) WW

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Wayco Wayne_2

Here's one with the Flat Plate drawn in place of the boiler. WW

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hot_rod

or

two solar tanks, single coils, each.
On issue with pulling heat from the upper coil is it has fairly low output without circulation around it. You also limit the solar-harvest-ability when you use a boiler on the upper coil.

Tie the boiler and upper coil in with a P/S or HydroLink (figure 29a in I-dronics 3)

Or two single coil tanks with one as SDHW and the other for hydronic loads. Caleffi has a 3 way zv that will attach right to the bottom of the Solar Pump station. I'm installing one at Caleffi, Milwaukee today, I'll get a picture to you.


Also a motorized mix valve with OD reset on the solar tank output will maximize the amount of energy you pull.

You always want to draw the solar tank(s) down to the lowest possible temperature every time, to really leverage your solar.

How many panels are you installing, give me you loaction and I'll run some calcs.

Don't get carried away with complicated piping if you only have 10,000 btu per day to move around

hr

Wayco Wayne_2

Thanks for helping HR

I'm installing 4 flat panels in MD West of Baltimore. I will check out the I dornics lit on line right away. WW

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klaus

Drawings

"(Gawd, I love to draw with this program. What fun!)"

What program are you using WW? I'm looking for a user friendly program, easy to learn, and not too expensive. Fun would be a great bonus! (Am I asking for much!)

I've been following most all the solar threads pretty closely. I'd like to tie it in at my house (experimental test bed ) with my GSHP and in floor.

Are you doing flat plates or tubes? I'll be anxious to hear what piping route you choose and how you come out.

Good Luck, Rich L

Metro Man

solar tie in

Just throwing that out there. Installing a mod/con kind of changes things. But still I would isolate solar storage.

For instance..... early in the morning, cold (70*F) solar storage, and all loads are calling for heat. Your reciring to the top of the storage tank for heat. Top of tank temps are 110*F (or more) from the heating loop returns.

Edit: Top of tank is actually whatever you set as a low limt from Polaris... Opps..

Sun comes up to heat solar storage tank but tank is already warm due to this heating. Solar does not energize until there is a good delta T. Solar then does it's job to heat tank. Granted there is stagnation in tank but you have still heated the SOLAR storage tank with gas.

This is just an inherent problem with a pressurized solar storage tank that is dual purpose.

Just my opinion and something we would never do.

Metro Man

hot_rod

Some energy data

From the NASA site. It shows energy for various months. Starts with January and ends with monthly average of 4.74

This reads in Kwh/ square meter/ day. Are you thinking 4- 4X8 panels @ 120 square feet of collector?


Geometry Information Elevation: 1519 meters
averaged from the
USGS GTOPO30
digital elevation model
Northern boundary
40
Western boundary
76 Center
Latitude 39.5
Longitude 76.5 Eastern boundary
77
Southern boundary
39
Show A Location Map


--------------------------------------------------------------------------------
Parameters for Sizing and Pointing of Solar Panels and for Solar Thermal Applications:
--------------------------------------------------------------------------------

Monthly Averaged Insolation Incident On A Horizontal Surface (kWh/m2/day) Lat 39.17
Lon 76.37 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Average
22-year Average 2.59 3.41 4.47 5.67 6.35 7.03 6.76 5.97 5.19 4.20 3.01 2.25 4.74


--------------------------------------------------------------------------------

Minimum And Maximum Difference From Monthly Averaged Insolation (%) Lat 39.17
Lon 76.37 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Minimum -14 -13 -18 -14 -6 -11 -10 -12 -9 -20 -18 -29
Maximum 10 24 25 11 9 11 10 9 11 11 14 18

Parameter Definition

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Wayco Wayne_2

It's Siggy's

Hydronicad. Simple and inexpensive. Even I learned how to use it and I lost massive amounts of brain cells in the 70's. www.hydronicpros.com should get you there. WW

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Wayco Wayne_2

You're getting me closer to agreeing with you.

However let me play devils advocate. If the boiler has to be on overnight, (and it will. There's never enough storage for overnight) the top of the tank will be warmed, however the bottom will still be cool. To quote Hot Rod, you must use it or lose it. To me that means turning your thermostats on full during the day while your at work. I know it seems counter intuitive to turn the programmable tstats up higher while your at work, but why not charge the radiant floors and keep the tank cooled down to get the most out of your collectors. The top of the tank warmed by the overnight cycle will be quickly depleted of it's heat once the boiler of back up heat it turned off. Some kind of over-ride may be needed to keep the main heater off and let the solar try to keep up.

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Bob Gagnon plumbing and heating

Simple Solar Space Heating

How about this diagram Wayne? Staging two tanks like this allows you to go long periods without any backup heater in the summer. One dual coil tank and one single coil tank allow more storage for the summer, the tanks don't have to be this big, during the heating season your house will act as a storage tank. Run your delta tee controller off the small tank in the summer to get increasingly hotter temperatures, and run the delta tee controller to the larger tank during the heating season to collect the maximum amount of low temperature BTU'S. Leave your thermostat up to about 75 degrees in the heating season, to keep the larger tank as cool as possible to harvest more BTU'S. Put a low temp cutout switch to interrupt the heating pump when the tank temperature drops below 90 degrees, then you come home and take all your showers the larger tank may drop to about 60 degrees. The next morning you will only have to wait till the collectors get to 65 degrees to start harvesting BTU'S. I think piping solar this way will make it far more efficient than favoring the domestic and sending any leftover energy to a radiant system. Maybe twice as efficient!

Thanks, Bob Gagnon




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Mike Dunn

I drawing I did for a client

Here is a drawing I came up with but haven't given the client yet. I am still mulling over if this is the best scenario. The dump zone is for a future pool.

I am trying to figure out how to control it so in the winter I spend less btu's on DHW and more on the space heating.

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Mike C._4

Spitballing ideas

I am just wondering about using two alternate heat sources for this system. I suggest you go over to www.hearth.com and go to the boiler room. They have many ideas to mull over for storage solutions. It wil be a lot to absorb.

Hope this helps.

Mike

Bob Gagnon plumbing and heating

Supplemental Solar Space Heating

In my drawing I use the solar heating for a separate supplemental radiant panel, that way you can keep your tank temps low all winter long, harvesting the maximum low temp BTU'S, while supplying a portion of your heating needs every sunny day during the heating season. You would simply run the supplemental solar radiant panel at the same time your other heating system is running.

Thanks, Bob Gagnon

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klaus

Supplemental panel

Neat idea Bob! What do you use for a supplemental radiant panel? Could a guy use a panel radiator type heater?

Thanks, Rich L.

Bob Gagnon plumbing and heating

You Could

But I think using aluminum plates in an inside wall or ceiling near your living room couch or bathroom might be the best option, micromanage those valuable BTU's, put them right where you need them.

Bob Gagnon

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kpc_34

how does....

water get from the solar tank to the marathon tank? Shouldn't there be a bronze circ?

Mike C._4

Supplemental Solar Space Heating

Actually, this is the plan for my system. A dedicated solar storage tank for getting low temp btu's should give much better performance than combining with a high temp source .

Mike

kpc_34

I still...

don't see how the water from the domestic tank actively gets from the solar tank to the marathon tank. Looks to pasive. kpc

kpc_35

anyone?

hot_rod

it flows

into the marathon as water (dhw) is drawn from the tank. You wouldn't want to recirc the tanks as you want to stratify the solar tank for best results.

hr

kpc_36

but long periods

of inactivity or little use will only make the eletric come on and not use the solar...seems like a waste.

hot_rod

If that is a common

occurance, little or no activity, just install a 3 way zone valve to "select' which tank you draw from. Pull the solar down to the lowest useable temperature then valve over to the back up tank or source.

An instantanous WH is another option. It has little to no capacity of it's own and pulls from the solar every time.

The best way to maximize solar harvest is to pull that solar tank to the lowest possible temperature every day. If you go on vacation for a week the solar harvest certainly lessens. Use it or lose it!

No draw, or no DHW use = no solar gain or harvest. If the tank is warm from days of no use, you have no load for the solar to charge, simple as that.

hr

Darin Cook_5

Solar Efficiency

Alot of folks these days have appliances with timers on them. I tell folks to try and use hot water during the day when the panels are pulling btu's. Run the dishwasher and the washing machine during the day like 1:00 pm or so. There are alot of ways to make your solar more effective, you just have to change your schedule slightly.






Darin

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kpc_36

my thought is...

I have a job w/ 8 panels. twin coil amtrol... 12 people at the college "dorm". The period of use will be early/ mid am where the night before has had no sun. 8-12 showers will use up that 80 gal. quick... passive 120 gal won't work in my mind, the buderus engineer calls for 240 gal storage.

hot_rod

what size panels?

somewhere in the 1.5- 2 gallons of storage per square foot of collector should be the target. 240 gallons or more, perhaps.

Are the dorms a year around use? Sometimes empty summer buildings could require some load shedding method. If there are no summer loads you might upsize the storage, use overheast protection, and re-cooling function available on the solar controller.

hr

kpc_36

Buderus

SKS 4.0 flat panels.. about 26 sq ft. each ... 8 going up. It will get year round use.... hence I presume 240 gallons of storage to dump into.