NachoBird - Wood Master to Buderus connection questions

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Old 03-03-14, 01:24 PM
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NachoBird - Wood Master to Buderus connection questions

NJ Trooper, I am sitting here reading through many of your threads and answers to some of the boiler problems and I would just like your opinion or "help" on a few things....

Yesterday a friend of mine came over and helped me "tie in" an outdoor wood furnace (Wood Master 4400) to an indoor boiler (Buderus G124) and an R 2107 sits atop running the show.

The Wood Master has an ETC (electronic temp control) on the side of the unit that is set for 180 high temp and 170 lower temp. Once the water in the furnace jacket hits 170, an electric blower located in the door of the unit stokes the fire until that temp hits 180 again)

The backside of the Wood Master has a Taco 0011 sending the hot water into the house and eventually to a 50 plate bronze heat exchanger. This line is currently hooked up to the TOP LEFT hole of the exchanger. The BOTTOM LEFT hole has pex going right back out to the Wood Master. (one continuous loop running the 170-180 degree water all of the time)

The TOP RIGHT of the heat exchanger is currently piped to the coldest returns from the baseboard heat as well as the coldest return from the DHW tank sitting just below the furnace. (This would be the Buderus Logamax) The BOTTOM RIGHT of the heat exchanger is now piped into the cold intake of the boiler.

(I do hope this is making sense, because it is confusing the heck out of me!)

My questions are as follows:
1) How come my R 2107 reads BOILER TEMP 160 when the outside furnace reads 180?
2) How come I cannot seem to get my DHW circulator pump to come on and use the same heated exchanged water as the furnace is using in order to heat the DHW tank? The DHW eventually drops to its low point and the Buderus actually fires to warm the water? What the heck? Do I need an aquastat for that? I was under the assumption that the R 2107 has an aquastat in its program to handle this...
3) If your screen name is NJ Trooper and I happen to live in NJ, perhaps you could just come and take a look at the entire setup? I would gladly compensate you for your time and efforts. I know that this Buderus setup is ingenious and I just need to familiarize myself with exactly what we did wrong, or did not do completely right.

Any help or comments would be greatly appreciated.

Thanks so much!
Glenn
 
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Old 03-03-14, 03:15 PM
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Hi Glenn,

I think I'm going to move this to it's own thread, might attract more attention from others as well if it's a new thread, I'll put NachoBird in the title so you can spot it easily.

Let me think about it for a while... in the meantime, can you take a bunch of pics of the system to show all the various bits and post them here... it helps to see what you're working on.
 
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Old 03-03-14, 03:31 PM
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This is one I will be chiming in on this one as well. Plenty of pics showing the entire system, where the house circulator is located on your system, and where the HX is located with respect to the rest of the system.
 
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Old 03-03-14, 04:00 PM
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This is one I will be chiming in on this one as well.
I was hoping you would!.............................
 
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Old 03-03-14, 05:22 PM
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Glenn,
I looked up the R2107 manual, but I don't see how this is going to help you heat the DHW or the baseboards without "bypassing" your boiler altogether.

Without seeing pictures, I can only guess how things are connected, but I can get a pretty good idea from your description...

The circulating hot water from the outdoor wood boiler will help heat only when water is moving on the other side of the HX for either the baseboards or the DHW. If your DHW temperature drops, the indirect tank will call for heat and will fire the boiler and start the circulator. You would need a separate aqua stat and possibly other items to do it correctly.
 
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Old 03-04-14, 06:19 AM
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I will take pictures and post them for you guys to see.....and thank you for your anticipated help.
Glenn
 
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Old 03-04-14, 06:35 AM
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When I read your first post, I thought... " That heat exchanger isn't piped properly "

Looking at the WoodMaster manual, it seems that I was right.

The HOT SUPPLY FROM the woody needs to go in the BOTTOM and out the TOP, while the home system needs to go IN the TOP and OUT the BOTTOM.

I think you have the connections to the woody reversed.

You want 'counter flow' on the two sides of the HX for maximum heat transfer.

See page 10 of the manual.

I don't think this is the total solution though, but will maximize the heat transfer across the HX.
 
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Old 03-04-14, 06:49 AM
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That manual is really lacking on piping details for installation... maybe there's another manual for that? What manuals did you get with the Woody? Are there piping diagrams in the manual?

Why did you choose to differ from the factory default settings of HIGH SP 170 ? I noted that you've gone up to 180...

You used the insulated PEX from the woody to the home, correct? What size PEX is installed?
 
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Old 03-04-14, 08:45 AM
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I think the theory behind setting the Woody at 180 high and 170 low was to not be anywhere near the default of the Buderus. We didn't want to take the chance that the Woody sends 160 degree water and accidentally tell the Buderus to fire off of propane. (does that sound right?)

Yes, I did install 5-wrap O2 barrier insulated 1" PEX underground to the house. Then for the inside run just used O2 barrier 1" PEX to go to boiler.

I am going to post some pictures for you. Take note on the Heat Exchanger Diagram. When we physically blew air into OUTLET #1 ( Top Left ) it came back out of OUTLET #2 ( Bottom Left ) and this was the reason we hooked up the way that we did.

I have looked at the Manual for the Woody on pg. and see what you are talking about, but if you look how we piped, isn't it the same thing, in essence? It's just upside down, I guess....? Tell me your thoughts please, and thank you so much for your interest in getting to the bottom of this.

BUT, as a side note - let me just say that after my first thread comment yesterday, I changed my DHW temp on the Buderus from 130 degrees down to 120 degrees. I had a theory that if and when I utilize DHW in the house, and let's just say that I am taking a shower.....the DHW tank has a capacity of 42 gallons. So if I were to utilize 20 gallons of that, then the cold water filling the tank would mix with what was in there. That water was, what I theorized as TOO COLD for the Woody to keep up with and try to heat at such a fast rate. The Buderus was calling for it to be 130 all of the time and since the Woody couldn't supply enough BTU's possibly, then the Buderus HAD to fire in order to keep up the demand.

Now that the DHW is lowered to 120, all zones of heating house are working correctly and operating when a thermostat calls for heat. But, if the DHW goes down to 110, that's when my ZONE 4 pump (DHW pump) comes on and all other zones will shut down. This R 2107 gives preference to DHW in all cases. Once DHW is satisfied with temperature, then the remaining zones will kick back in.

Does this make sense?
Again, please see pictures and if you need me to send more or explain more, please advise...

Thanks!
Glenn
 
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Old 03-04-14, 06:27 PM
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Glenn,
I had pictured in my mind what you are showing.
You theory on the DHW sounds right, but it would be interesting if you could take some temperature measurements on the input and output sides of the HX for the DHW feed while someone is taking a shower. Curious to see if the HX can keep up with DHW demand.
It does seem like a good move to use the priority zone. I do wonder how things work when the hot water tank gets to the low limit any nobody is drawing hot water...I guess the boiler fires to heat the tank, correct...all the while you have 180 degree water only a few feet away. I have a similar issue with my system...

It seems like you have a simple way to hook up the woody to your existing heating system. It does not allow your house to overheat.

Bottom line, is everything working as you would like it to work now that you have lowered the DHW tank thermostat setting?
 
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Old 03-04-14, 08:30 PM
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Let me say again that this is not the root cause of the problem, but a possible contributing factor, and that I haven't had time to give much more thought to this, sorry...

But, you said:

I have looked at the Manual for the Woody on pg. and see what you are talking about, but if you look how we piped, isn't it the same thing, in essence? It's just upside down, I guess....? Tell me your thoughts please, and thank you so much for your interest in getting to the bottom of this.



No, not the same thing. You want the HX to be piped in 'counter-flow'. The way you've shown it is that both flows are going the same direction. You want the flows to be in the OPPOSITE direction of each other to get maximum heat transfer.
 
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Old 03-05-14, 08:43 AM
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Ok, great. So for the "counter flow" to work....what should I do with the current configuration that I have right now in the pictures?

Should I:

1) Just change just the Woody Pex lines (make the HOT come into the to bottom into my OUTLET 2 and have the COLD go out of the top OUTLET 1?

OR

2) Just change the inside boiler lines (make the HOT go into the top into OUTLET 3 and the COLD to OUTLET 4?

OR

3) Change ALL like stated above in #'s 1 & 2?

I am reeeeealllly confused now..... Oh, God! lol

Thanks,
Glenn
 
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Old 03-05-14, 08:52 AM
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Hey ThomasDB,

I have watched the temp of the DHW fall to the low point of 110 degrees. At that point the furnace will NOT fire - that is when ZONE 4 pump kicks on and takes priority over the other heating zones of the house. Once the DHW is satisfied with 120, then the other zones will resume normal operation.

The only other concern is, just as you stated above, what happens when I try filling my garden tub (90 gal capacity, but in all reality about 70 gals with a person in there) and the DHW tank is emptied. Will the Woody be able to supply enough to the HX in order to keep up with demand? The Woody is sending 180 degree heat into the exchanger all the time....so in essence it should, but once you have 55 degree well water filling the DHW tank, it will take quite a bit of BTU power to heat that again - thus the likely possibility that the propane fires the Buderus.

Hmmmmm.....
 
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Old 03-05-14, 09:18 AM
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what should I do with the current configuration that I have right now in the pictures?
Make it look like what's in the install manual, which I believe is Woody IN BOTTOM LEFT and OUT TO WOODY, top right.

Not looking at the manual at this moment, but I think you just need to swap the lines to/from the Woody.

Actually, you could swap either one or the other because it's essentially the same thing, as long as the two flows are in OPPOSITE direction through the exchanger.

As I said though, don't expect HUGE difference doing this, but it WILL give better heat transfer across the exchanger.
 
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Old 03-05-14, 09:24 AM
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What I see as a design defect on MOST wood boiler installations is that they don't provide a place to 'warehouse any BTUs'.

So when the heat or DHW isn't calling, there is no heat being transferred from the woody to the heating system because the heating pumps aren't running and there is no flow through the heat exchanger.

My opinion is that there should always be a pump on the inside boiler side of the heat exchanger that circulates heated water out of the the exchanger and into the boiler and maintains the boiler HOT at all times. This 'warehouses' some BTUs such that they are available for immediate use when there is a heat or DHW call. With no waiting for the heat exchanger or fire to play 'catch up'.
 
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Old 03-05-14, 02:14 PM
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I agree with NJ on the storage aspect, and he is right with regard to HX flow.

Glenn, can you get some temp measurements on the woody inlet and outlet at the HX before reversing the pipes, then again afterward. Then we would know how much direction plays a roll and can use this in any future Hx flow questions for others.
If you are interested, search "System 2000 with wood stove" and you will find a thread from a few years back showing a photobucket link to my system (with a 72 gallon storage buffer). I have one circulator doing the entire heating job for the house, but then again, I don't have to worry about outdoor pipes freezing. The buffer tank takes care of the 'overdraw issue', but does not solve the 'no water draw' for a long time issue.
 
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