Outdoor wood boiler using solar controller


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Old 12-19-09, 04:32 PM
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Outdoor wood boiler using solar controller

HI:

Dont know if I am in the right place but I read one of NJ Troopers threads and was thoroughly impressed and suspect he may be able to solve my problem (if I can explain it!)

OK Let me set it up

i Have a weil mclean indoor boiler (radiant heat) - propane and an out door wood boiler. I have a heat exchanger between the two.

I have an "H" set up in the piping coming from the WOOD boiler to the exchanger. In the crossbar of the H is a zone valve and then in the upper left is a zone valve (could have just used a 3 way zone valve but the home center didnt have one)

The way I have it set up is if the wood boiler is >125 it opens up the valve to go to the exchanger (AND CLOSES THE ONE IN THE MIDDLE OF THE h) . If its less then 125 it just sends the water back to the boiler (ONE IN THE MIDDLE OF THE H STAYS OPEN AND THE OTHER ONE CLOSES )

Problem with this is I am losing heat - If the wood boiler is at 120 and the return water in the house is at 110 I am using propane and the wood heat is just staying outside . OK so I could set the aquastat down to a 100 but then what happens is if the propane goes to 130 its now heating the wood boiler AND ACTUALLY REVERSING THE EXCHANGE PROCESS
so I had to settle for setting the aquastat at 125 .

So what I needed was a differential controller the type they use in solar heating so I could compare the temp of the water coming baCk to the propAne boiler to the temp of the water in the wood boiler and opeN / CLOSE the vaLves based upon that.

So I bought this one http://www.solarwaterheatingspeciali...01/sr868c8.pdf

as the dealer who sold it to me assured me I could do what I wanted. UNfortuatnely the dealer has no idea how this thing works.

I put some specifics as to how this works below if they are needed.

Suffice it to say that I have this controller figured out so when I get the temperature difference I need it doEs activate a 120v circuit.

But here my problem - my zone valves are 24 v.

So (finally) heres my ?-- How can I get one zone valve to open and the other to close and then vica versa using an "on then off" input from 120 v WHEN THE ZONE VALVES ARE 24V ??



INfo on the controller that i have figured out :

120v feeds to the "input" ports on the Out put side

T0 - t4 ARE LOW VOLTAGE

WITH NO TEMPERATURE DIFFERENCE I HAVE 120V AT H1 AND 0 AT r1 p1 AN p2


i PLUGGED SENSORS INTO t1 AND t2 AND USED A HOT CUP OF WATER TO GET A TEMPERATURE DIFFERENTIAL.

INDEED WHEN THERE IS A DIFFERENCE i GET 120 VOLTS AT
p1

SO NOW I NEED TO FIGURE OUT HOW TO GET THIS 120V TO OPEN AND CLOSE THE 24V ZONE VALVES.

i WOULD ALSO LIKE TO USE THIS CONTROLLER TO DO THE SAME TYPE OF THING TO HEAT MY dhw ON A SEPERATE ZONE FROM THE WOOD BOILER BUT i DONT SEE HOW IT CAN BE DONE (DEALER SAID IT COULD)

alternatively IF THERE IS AN EASIER SYSTEM FOR DOING DIFFERENTIAL TEMPERATURE CONTROLS BY ALL MEANS SEND ME TO IT !!


tHANKS FOR YOUR TIME
 
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Old 12-19-09, 06:27 PM
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Offhand, as a quick response just so you know someone is here in the Blizzard of '09, perhaps the easiest thing would be to use a 120 V to 24 V transformer to operate the valves. But I must say that I haven't completely digested your setup yet... need to read it again.

OK, I read it again, and maybe you need a relay also...

Can you scribble up a diagram and take a picture of it and put it up on photobucket or something?
 
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Old 12-20-09, 10:34 AM
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posting a schematic

HI:

I have drawn a schematic and I am looking for the "manage attachment" button to insert it but cant find it anywhere ?

What am i missing?

Mike
 
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Old 12-20-09, 12:12 PM
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You can't directly attach stuff to the forum. If they are photos, or .jpg scans of drawings, you can use a photo hosting site like photobucket.com and link to your album.
 
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Old 12-20-09, 12:36 PM
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I had a similar dilemma with a solar array with a boiler backup.

first, trooper is right. you need a 120 to 24 v transformer. i have mine mounted to the cover plate of a metal junction box. (the wires come out the back of the transformer. you can't get these at hd or lowes. i had to get them at an electrical supply store. you just have 120 in and 24 out. i used them to power 24 v ice cube relays and thermostats and controllers.

i finally went to either the solar array or the boiler was operating (only one at a time) because i did not want the boiler heating the solar array. the amt of sunlight and solar array temps changed so fast, i had to operate one or the other. originally i thought the solar could preheat the boiler loop but i also had the problem of reduced flow to the solar array when the boiler circulator turned on causing the array to get too hot. I now have the boiler on a timeclock. it soes not start until after the sun goes down and goes till 8 am, then turns off. i did this using ice cube relays.

i am interested in your H setup though and will watch to see how that is resolved. hope this helps
 
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Old 12-20-09, 04:39 PM
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Schematics

Hi Guys:
OK I put the schematics on Photobucket. I just dont know if they are going to show here

Here are the two links (is there a way to get them to show here??)
[edit NJT - yes, use the "IMAGE" link, the one that looks like a postcard, and paste the IMAGE LOCATION, or the DIRECT LINK into the pop-up box]





Ok so if you look at the boiler link. Start in the lower right at the wood boiler. That circulator comes on whenever the main circulator for the boiler starts . Now as it enters the house you can see the "H" I am talking about (just ahead of the aquastat.)

Heres how that works The aquastat is set for 125. If the temp is less than 125 zone valve 'A' closes and zone valve 'b' opens. THis now is just circulating the water back to the wood boiler waiting for it to get to temp (NIce to prevent freezing when you are not at home as well)

Ok so now the wood boiler gets to 125 when it does it closes zone valve B and opens zone valve A and now the hot water from the boiler can go to the heat exchanger and then back to the boiler

Note that both of those zone valves are 24 v off of a transformer.

On the propane boiler side its pushing water through the radiant heat system. WHen it come back you will see that there are two circulators The main one for the boiler and then one I installed to grab the return water and send it through the heat exchanger (I guess I could have just plumbed the heat exchanger right in line with the main circulator but for some reason I didnt ).

So this always runs that way when the boiler is on. If the wood boiler is over 125 it can grab heat (ie zone valve a is open b is closed ) if not then the wood boiler side is just stagnant At the heat exchanger (zone valve a is closed and b is open )

The problem with this system is that I am losing heat outside. If the water returning from the house is 110 and the wood boiler is 120 zone valve a is not open and that heat is just staying outside.
Now I could drop the aquastat setting to say 100 but heres the problem with that. Sometimes the propane boiler will push to 135 - now I am basically reversing the heat exchanger and heating 160 gallons of water that's in the outside wood boiler - that not efficient.

Hence I wanted to get a system that would compare the temperature of the water returning from the house and the temperature of the wood boiler water. When the wood boiler is greater than the temp of the water returning from the house -- zone valve a would open when its less it would close (and b would do vice versa).

So I bought the solar controller and indeed (as described below) when there is a difference of 8 degrees it activates a 120v circuit .

The question is how do I get that 120 v circuit to move the 24 volt zone valves??

I guess I could just take out the 24 volt zone valves and put in 120's but how would the 120's work? ie would they move to the opposite pole when deenergized? or is there a way to use the 24 volt ones.


I also put a pic of the solar controller schematic . There are two low voltage sensors. When the temp difference is 8 degrees (or whatever I choose to set it at) . This activates p1 Pi is a 120v circuit. So I need that 120 volt circuit to open zone valve a and close b when the difference is 8 degreees or more and close a and open b when its less.

Zone valves are currently 24 volts
P1 activates when there is a temp difference of 8 degrees enrgizing a 120 volt circuit

As I am thinking about this I think the key question is how do the zone valves work. If you energize one does it always open and then if you deenergize it does it always close ?

But even if thats the case this wont work for me cause I need one to open and the other to close an then to reverse that

So have I thoroughly confused everyone ??
 

Last edited by NJT; 12-20-09 at 05:26 PM.
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Old 12-21-09, 08:09 AM
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i have honeywell 24v zone valves. when energized, they activate. that can be either opening or closing, depending on the type of valve you need. i have some of both in my setup. when de energized, they are spring loaded and return to the original position without power. on my valves, there is a lever you can push and lock into a slot to manually open the valves. when you push the lever out of the slot, it will automatically go to the original position. just as an example, i have to have an emergency setup if the power goes out. if i lose power, all my zone valves will automatically close except for 2, and they open up a photovoltaic circuit and pump to keep the array cool.
 
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Old 12-21-09, 08:21 AM
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i have a solar controller that operates similarly. when the difference varies from the setpoint by a certain amt, it activates P1, P2 or both depending on the mode you have it in. you can use that 120 v P1 or P2 leg to be the load side of the power input of a 120/24 v transformer. thus, when P1 gets power, it gives power to the transformer and completes the 24v circuit to the zone valve which activates it( either opens or closes depending on which you have). when the P1 power is cut, it breaks the transformer power, and the valve automatically returns to its original position. this is how zone valve controllers work. i have a taco zvc 406. i also have some running just like i described above.
 
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Old 12-21-09, 08:36 AM
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Just for future reference,
The Tekmar 155 and 156 have dry contacts, thus you don't need to worry about 120 to 24vac transformers.
The end switch of the NC zone valve could be used to trigger the house side circulator.

Its a simple set-up, but pretty functional.
There are also some nice mechanical valves that divert flow away from the heat exchanger until it's up to a certain temperature.
 
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Old 12-21-09, 09:02 AM
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ZOne valves

Hey THanks for the info I have a question mtmnttop.

SO if the zone valves are normally in one position (ie the spring closes them) the problem is that I need one to open and the other to close and then vica versa

so when not calling for heat I need A closed and B open

B cant be open unless there is power to it somehow I would have to reverse that situation (so that B is open when there is no power)

The other choice is to go to the three way valve. Does anyone know how that works - ie with power its open one way but not the other and then it reverses with power. If that were the case then a three way valve would work just
fine

MIke

PS almost took a position in Red Lodge, montana once -
 
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Old 12-21-09, 09:12 AM
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from what i can figure out with your situation, it sounds like you need one normally open (NO) zone valve and one Normally closed (NC) zone valve. when they have power applied, one will open and the other will close. and vice versa, when the power is cut one will close and the other will open. you can run both zone valves off of a single 120-24 v transformer. am i understanding this correctly? just as a note to the earlier post, i was not able to find a normally open zone valve with an end switch if that ever becomes a concern of yours. normally closed zone valves with end switches are common.
 
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Old 12-21-09, 02:02 PM
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NO and NC zone valves

Thats exactly it mtmtntop. I need one that NO (Normally OPen) and one thats nc (normally closed) - then they will reverse when powered on

Are you saying that they dont make em that way.

IF not how does the threeway work. Ie does it open one way when energized and then the other when deenergized ?


Mike

PS I also emailed honeywell to see what they say - will let ya know
 
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Old 12-21-09, 02:23 PM
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they make them that way and they were about the same price. when you go to the plumbing store you just have to tell them you need a normally open motorized zone valve. here they did not stock it, i had to get it the next day as it is not the usual request.
the number on mine is V8043B1207 and it is a 3/4" sweat ...not sure if those numbers indicate diameter and type of fitting.

i am assuming the one in the H opens when you apply power so that is a Normally closed (NC) zone valve. you need the opposite for the other valve.

this part of my response is more of a question as i am not very good at circulators. it seems to me you may need a one way valve somewhere to make sure the flow through the exchanger goes the way you planned. like in the cold return loop just before b so it could never go through the H then to the heat exchanger, but rather always back to the boiler. i had to put one of these in my loop.
 
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Old 12-21-09, 03:35 PM
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One way valve

Hi mtmtntop

Thanks for the info. That means I should just have to change out one zone valve

I dont think I need a one way valve as the zone valve basically prevents circulation in any but one direction. ie if 'A' is open 'B' is closed and it can only go through the exchanger.

If 'B' is open and 'A' is closed it can only go back to the boiler (granted it could go to the exchanger then down back to 'A' valve but since 'A' is closed it cant really circulate in that direction.)

I have been looking at my zone valves - there are three electrical ports on each side of the back end . I wonder if one side makes it NO and one makes it NC

yet that wouldnt make sense cause if its spring operated that's a mechanical system and would only operate in one direction.

I am going to have to see if I can find some literature on that

Otherwise it looks like I just need to figure out what type of zone valves I have an purchase the opposite

Mike
 
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Old 12-21-09, 03:39 PM
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the terminals on the valve cannot change the NO NC nature of the valve to my knowledge. my plumber helper made me buy different valves.

maybe someone else can help with this question re the one way valve. i do not think you are supposed to have pressure against the back side of a closed zone valve, which is what would happen if a were closed and b were open. again, i am not sure about this, its just a question.

sounds like you are on your way.
 
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Old 12-21-09, 04:19 PM
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The valve body is the same, it's the operator that defines the normal position of the valve.
Direction flow against the arrow, or proper flow direction, usually ends up with a valve slamming closed and creating a nice water hammer effect.

Typically with closed spaced Tees, such as your "h" configuration there is little to no pressure drop between the to branches of the tees and therefore there will be no flow through them. The more distance you create between them the greater the change of migration, or ghost flow.

I check valve will usually stop this (needs to be a weighted check or a spring check) provided the pressure difference is not too great. Much cheaper and easier to put in now.
 
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Old 12-23-09, 05:09 PM
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usING A RELAY

hEY gUYS i GOT THE FOLLOWING RESPONSE FROM wHITE rODGERS only I have no idea how to hook it up

They want me to use a single pole double throw relay - I am assuming that these come in 24 v and I put it between the transformer and the one zone valve? But I am not sure how to wire it


"you may want to consider using a SPDT relay to change the position of the valves. A SPDT relay
would provide one Normally Open and one Normally Closed contacts. When
actuated by energizing the coil it would close the NO set and open the
NC. When de-energized it would open the NO and close the NC."
 
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Old 12-24-09, 09:24 AM
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yep, that would work. these are what i called ice cube relays and they do come in 24 volt. i have some bookmarks for these and how to wire them for NO and NC and will look for them. i have 5 of these doing different things in my system now. they are just great and cost about $16 apiece.
 
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Old 12-24-09, 11:14 AM
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If I understand this correctly, you can use the valves you have in place right now and use the relay to manipulate the power to the valves.

here is what the kind i have used look like.
DPDT (Double Pole/ Double Throw) OCTAL STYLE ICE CUBE RELAY, 120 VAC Coil, 12 Amp rated


you buy a base with the relay, they come separate

there are 8 screw terminals on the base. the relay plugs into the base. terminals 2 and 7 get the power from the source. your diagram indicates that when P1 is activated, it connects the 115v circuit. so you could use a 115v relay, here's how. use the P1 leg from your controller as the hot side of the relay power, screw7. run the neutral to screw 2. this will energize the relay when p1 is called by your controller.

to control the valve in the H , you would run 1 wire from your 120-24v transformer output to screw # 1 and another from 3 to the H zone valve (NC). so when the controller activates P1 the relay is activated terminals via 2 and 7, it will close contacts completing 1 and 3 and open the NC zone valve in the H. you have the other valve wired from the same transformer to terminal 8, and from terminal 5 to the normally closed (NC) zone valve. When there is no power coming from your controller, the valve will be open. when P1 is activated, it will open the points between 8 and 5 and cut the power to the valve, which will then close. so when 1 and 3 have power, it will cut the power to 8 and 5. when 1 and 3 lose power it will connect 8 and 5.

i know this sounds confusing, but it will make sense when you have the relay in front of you. i have a relay wired almost identical to this. i waited for the P1 lead to provide power to the relay and then checked the pairs of points for continuity with a meter before i hooked the leads to the screws. its concept is pretty simple. a set of points open when power is applied to the relay and a set of points close when power is applied to the relay. i hope this is useful info for you.
 
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Old 12-24-09, 02:51 PM
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Nobody has mentioned just using an Automag zv that "fails open" and then use a honeywell zv , or similar that "fails" closed.

Good luck
 
 

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