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Noobie to solar but not to heating looking for experts (7 Posts)
Noobie to solar but not to heating looking for expertsI am a HVAC tech with 20 years experience but I've actually never done anything with solar so I need some advice.
Ok guys so here is what I have:
Located in southern Maine-
28'x54' Ranch with a daylight basement on back side. Facing Southwest on the front side of the house. 7-12 pitch on the roof.
Three adults currently living in the house. Finished basement. 2 full bathrooms one 3/4 Bathroom.
Crown CT 35 oil boiler running 85 to 86% efficiency 90,000 BTUH. 6 heating zones and one zone for indirect domestic hot water. Zones fed by Taco 007 pumps and ARGO pump controller.
Mega-Stor horizontal 40 gallon tank under the boiler. Location- basement boiler room/laundry room.
Vermont castings Defiant woodstove 75,000 BTUH. Location- basement den center of house with a draft hood above it and a large floor grate to the main floor.
36,000 BTU 10 SEER R22 central air conditioning system. Location- AHU in attic and CU out back.
Silicon Solar (80 gallon??) two coil, two sensor locations, option for electric heat element. Solar tank never used.
Used 15 tube solar collector year unknown but older model. Needs at least two new tubes
large, deep aluminum finned copper tube hydronic air coil never used 1' copper in and out.
several different size heat exchangers
A little about myself. I am a HVAC tech. I have been in the trade for 20 years but have never installed a single solar system and honestly don't know a lot about them when you get into the real techy stuff.
I mostly use wood to heat my house so the boiler only heat now and then and heat my domestic hot water all year. I burn 4 cord of wood a year and go through over 1000 gallons of oil a year. Some of the wood burning is a waste because the wood stove usually makes the house hotter than we need (75-80 degrees unless below 0)
I run the central AC when it gets really hot in the Summer. So July and August mostly.
So here is my vision that I need help with:
-Try to us the solar collector I have if it is worth using (???) or purchase a 30 tube collector
-Install the hyronic coil I have in the attic with two 12 volt automotive fans fed from a FV system to remove heat from the attic to heat my dom HW AND to cool down the attic. This should help keep my house cooler and help my AC system in the attic to be more efficient (Usually 120+ in my attic on a sunny day I the Summer)
-Use the solar tank I have to heat domestic hot water.
-Use my current indirect HW tank somehow
-Steal some heat from my woodstove to reduce the BTU output and to heat domestic hot water AND maybe a hot water coil in the duct of my central AC system
-Install a de-superheater on the central AC condensing unit to make the AC unit more efficient AND use BTUs removed from the house to heat domestic hot water.
So I need a solar controller or some sort of a PLC that can decide what pumps should run, valves should open, when they need to go on/off, etc. Also it would be nice if it had data logging. I've been looking at the Resol Deltasol units.
I can get HVAC and plumbing parts at cost through local supply houses like FW Webb.
I want to do this as cheap as possible to get the best payback. I was thinking $3000 max to get something up and running making how water then add on a little here and there. I've heard you can save some money by not buying the package pump set ups so I will be building my own set up as I go along.
I like the idea of a variable speed pump or pumps but don't know what I need to do this. I deal with Grundfos Alpha pumps a lot but they vary their own speed and don't take an external control input.
I was thinking for now pipe up the solar tank, pipe up the air coil in the attic and install two automotive 12 volt fans on it. If I cant afford the solar controller I REALLY want/need just get a $100 one for now to get going (I'm thinking for what I want to do I'm looking at a $500+ controller)
Next step install 15 tube collector or buy a 30 tube and install it on the roof. OR install de-superheater on my AC system.
So what do you guys think?
Oh also what happens to all the built up heat when the tank is up to temp and the pump shuts off??
Some DHW pre-heatis what you can expect from 15 tubes, maybe 30 gallons per day. You can go to www.solar-rating.org and try to find a similar sized collector and get some performance data.
You will need a drip pan under that attic recovery unit. Warm air and cold water = condensation. And a means todrain it for winter.
Solar Attic sells those units for DHW and pool heat from attic heat. Maybe get some performance data there.
Hard to knbow how much DHW you use and how much the solar could offset. consider a solar tank with an electric element for back up if you want to get off wood for summer.
yeYeah I already have the catch pan. I surely hope it does condense humidity onto the coil. That would be a great fringe benefit.
I don't need an electric heater to get off would. As I stated I have an oil Boiler.
This forum is not very active I guess.
flat plate vs tubeUse that old tube collector for target practice. Buy 2 new flat plate collectors from your plbg. Supply house ( buderus makes 2 types). Evac. tube isn't well suited for New England
winters. Too much ice & snow buildup . Failure of tube Vacuum is always a problem as well.
Ok I think this is what I am doingFirst of all a million times I say thank you to Hot Rod Bob Rohr for his numerous replies to my email questions.
So I typed this up last night what do you guys think?
So I don't have a drawing done yet only a drawing in my head so far.
DOMESTIC HOT WATER SYSTEM
Major system components description-
1-Caleffi iSolar MX LTE solar control module (SCM)
8- Temperature sensors from SCM (S1, 2, 3, etc.)
1- Argo 6 zone pump zone control panel (ZCP)
1- Double pole double throw Summer/Winter switch (S/W Switch)
4 or 5-Taco 007-F4 IFC pumps (Pumps #1, #2, #3, #4, and #5)
1or 2- 3 Port, two way 24 volt zone valve (ZV #1, ZV#2)
1-Silicon Solar 80 gallon dual coil solar tank (Tank #1)
1- Super-Stor 40 gallon single coil indirect water heater (Tank #2)
1- Crown CT-30 cold start oil fired boiler (Boiler)
1- Sunmaxx 30 tube solar collector on roof top (Collector #1)
1- Hyronic air coil aprox 2'x4'x6" in attic space (Collector #2)
1- Copper tubbing bumdle on woodstove (Collector #3)
1- Hyronic air coil aprox 2'x3'x3" heat dump coil (HDC)
120 volt powered PLC monitors eight input sensors on system and flow sensor. SCM controls output relays for pumps and/or valves based on built in calendar scheduling, temperature input readings, or temporary manual settings. The SCM also logs all data received to a USB drive or a LAN BUS output to a PC. Data logged: recorded temperatures, relay outputs, GPM flow, etc.
Pump #1 pumps HTF from Tank #1 bottom coil (outlet) up to Collector #1 on the roof. From collector #1 HTF comes back to the bottom coil of Tank #1 (inlet)
SCM starts Pump #1 based on differential between Tank #1 S2 Bottom tank sensor and Collector #1, S1 outlet sensor and shuts down Pump #1 if S2 or S3 tank sensors measure a high temp. limit.
Pump #1 speed increases proportionally to the temp. differential between S2 Bottom tank sensor and Collector #1, S1Outlet sensor but lowers the pump speed to no lower than 30% of max speed.
OPTION A- Pump #2 pumps HTF from Tank #2 coil (outlet) up to collector #2 in attic. From Collector #2 HTF comes back to Tank #2 coil (inlet).
SCM locks out Pump #2 until after 12:00 P to allow a high temp difference between Tank #2 and air in attic space to ensure maximum attic cooling and water heating.
After 12:00P SCM starts Pump #2 based on a minimum temp. differential between Tank #2, S4 Sensor and Collector #2, S5 Sensor.
The SCM shuts down Pump #2 if S4 Tank sensor reaches high temp. limit set point AND Collector #2, S5 is at a higher temp than tank S4 temp.
If tank #2, S4 Sensor reaches high temp. limit AND collector #2, S5 Sensor is COOLER than tank #2, S4 Sensor---- Pump #2 is started to dump excess heat into attic through collector #2. This would most likely occur at night after a hot sunny day or on a sunny but cool day or in a vacation mode after Pump #3 dumped heat into Tank #2 (See Pump#3 description below)
Pump #2 speed increases proportionally to temp. differential between Tank #2 and Collector #2 but lowers the pump speed to no lower than 30% of max speed.
OPTION B- SUMMER/WINTER OPERATION OF PUMP#2-
S/W Switch in "Summer" position- Operation is the same as above but Sensor 5 is now called "S5A"
S/W Switch in "Winter" position-
S/W switch is switched to "Winter" position. This switches SCM from sensing Collector #2 outlet S5A to sensing Collector #3 outlet temp. S5B.
It also switches the position of ZV#1 3-port valve.
Pump #2 pumps HTF from Tank #2 coil (outlet) to Collector #3 on woodstove, flow controlled by ZV #1. HTF comes back to Tank #2 coil (inlet).
SCM starts Pump #1 based on differential between Tank #2 S5B Sensor and Collector #3 S5B Sensor and shuts down Pump #2 if tank #2 S4 reaches high temp. limit set point AND Collector #3 S5B is at a higher temp than tank #2 S4.
Pump #2 speed increases proportionally to temp. differential between Tank #2 and Collector #3 but lowers speed the pump speed to no lower than 30% of max speed.
Pump #3 pumps HTF from Tank #1 into Tank #2 If tank #1 S2 Sensor reaches 180F. The purpose is to dump heat into Tank #2, cooling Tank #1 and adding more preheating capacity to tank #2.
Pump #3 speed increases proportionally to the temp. differential between Tank #1 S2 Sensor and Tank #2 S4 Sensor but lowers the pump speed no more than 30% of max. speed.
Pump #4 pumps boiler water from the home heating boiler system, into the top coil of Tank #1 for hot domestic water when not enough collected hot water is available for showers, washing dishes, etc. and to sanitize the tank.
The SCM locks out operation of Pump #4 for low or no domestic hot water usage periods to allow adequate time for the collectors to heat up tank #1.
The SCM senses the top of Tank #1 through S3. If the S3 temp. is below 150 degrees AND the pump is not in a locked out period, the SCM sends a 24volt signal to "priority" zone #1 on the ZCP through a 120Vx24V RIB relay. The ZCP turns on Pump #4 (zone #1 on ZCP) and the boiler starts running to reach its limit switch. Pump #4 heats the top section of tank #1 to a temp. of 150 degrees at S3 then shuts off.
Pump #4 speed increases proportionally to the temp. differential between the boiler supply temp and the temp. of the top of tank #1 but lowers the pump speed no more than 30% of max. speed.
*PUMP #5 OR ZV #2 OPTION (May be added to system later)-
Pump #5 Option-
NOTE- Tank #1 has already got too hot and the SCM turned on Pump #3 which transferred heat into tank #2 in an effort to cool tank #1 and now tank #2 is getting too hot and reached an UPPER high limit set point on the SCM.
The SCM turns on Pump #5. Pump #5 pumps HTF from Tanks #1 and #2 (series circuit) out to HDC in garage then back to the tanks.
Pump#5 speed is constant and does not change.
ZV #2 Option-
NOTE- Tank #1 has already got too hot and the SCM turned on Pump #3 which transferred heat into tank #2 in an effort to cool tank #1 and now tank #2 is getting too hot and reached UPPER high limit set point on the SCM.
The SCM turns on ZV #2 which diverts HTF from Tanks #1 and #2 (series circuit) out to HDC in garage, then back the tanks
*It seems that this scenario would only occur on rare occasions such as:
A- a very hot, sunny, summer day with little or no domestic hot water being consumed.
B- a sunny day in the Fall or Spring when woodstove is being used with little or no domestic hot water being consumed.
OTHER SENSORS FOR DATA LOGGING PURPOSES-
S6- Senses Boiler supply water temperature at boiler
S7- Senses outdoor temperature
S8- Senses Attic temperature
PUMP #4 SUGGESTED SCHEDULE:
Pump #4 locked out from 8:00P to 4:00A and from 7:00A to 4:00P Monday through Friday. The SCM also locks out Pump #4 from 8:00P Friday until 7:00A Saturday and from 9:00P Saturday until 7:00A Sunday and locks it out from 8:00P Sunday until 4:00A Monday.
DOMESTIC HOT WATER PIPING DESIGN-
Cold water from well pump and well tan feeds into Indirect Tank #1.
Pre-heated water comes out of Tank #1 and into the bottom of Tank #2.
Hot water exits Tank #1 and then goes into a hot water mixing valve to temper water temperature to 120 degrees.
120 degree hot water feeds out to fixtures.
reformatted typingOk so,...Everything that was BIG AND BOLD TEXT when I typed it in Word is now tiny. The smaller text is now LARGE AND BOLD.
What the heck??
TLDRTry to keep it simple.
Any system that needs more than two or three pumps and one controller is probably too complicated unless it's your new hobby.
I advise against zone valves and timers.Superinsulated Passive solar house, Buderus in floor backup heat by Mark Eatherton, 3KW grid-tied PV system, various solar thermal experiments