What should I set gas boiler settings at?

timberframe

Member
Dec 11, 2013
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Mid Michigan
Tomorrow I will lite my first fire in my new wood boiler. I ran the pex water lines into the house and into a heat plate exchanger. From there I tied into the return water side of the Navien gas boiler NHB-080. I was planning on setting the set point at the wood boiler at 170*. My question is, what setting adjustments do I need to do on the gas boiler. Do I need to set anything up to avoid the gas boiler from firing up? Thanks for any info.
 

timberframe

Member
Dec 11, 2013
48
2
38
Mid Michigan
Tomorrow I will lite my first fire in my new wood boiler. I ran the pex water lines into the house and into a heat plate exchanger. From there I tied into the return water side of the Navien gas boiler NHB-080. I was planning on setting the set point at the wood boiler at 170*. My question is, what setting adjustments do I need to do on the gas boiler. Do I need to set anything up to avoid the gas boiler from firing up? Thanks for any info.
I thought I better add a little more info. The pex tubing is 1" going from OWB to indoor heat plate exchanger. The total run from the OWB to indoor gas boiler is 45'. The heat plate is a 20 plate with one inch ports.
 

leon

Minister of Fire
You have to decide if the gas boiler is going to be a standby heating
unit if the wood fire goes out.

You should have had all this figured out with your electrician before hand
as you have not mentioned where your circulator's are and how they are controlled.

You could just turn the gas off BUT the issue is how both boilers will be controlled if you have no
wood fire and no heat. You should have done your homework.
 

maple1

Minister of Fire
Sep 15, 2011
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Nova Scotia
Does the hot plate water circulate through your gas boiler if there is no flow in your zones? Or is hot water getting to your gas boiler totally dependant on return zone flow happening?

If it is dependant on zone flow, you will likely have quite a bit of short cycling when zones first call due to the slug of cold water that has to clear the boiler before the hot reaches it.

Should be able to tune it out or down some by lowering temp settings on your gas unit. I have no experience with those, others may be able to give more input.
 

timberframe

Member
Dec 11, 2013
48
2
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Mid Michigan
Well I got a first time fire lit today in the new wood boiler. It took about 5 1/2 hours to get the water temp to 135*. I have the set point set at 170*. When my OWB water got to about 130*, the gas boiler quit flaming on and it setting into circulating water only into my radiant floor zones. We are excited to get this boiler going. So far I haven't had to change any settings. That's good cause I wouldn't know how. I do have a question though, should I purchase a chimney cap to keep rain and such out? Also how often will I be adding water to the OWB?
 

timberframe

Member
Dec 11, 2013
48
2
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Mid Michigan
Sorry to throw another question out here, but having this being my first fire, I have another one:
There is a temperature control box on the OWB. Before I started my first fire, it read 62*. The water temp gauge on water jacket also was 62*. So I built a fire and set the temperature control set point at 170* with a 5* differential. Well it heat the water to 150*. Humm, so I set it at 180* and it heats the water to 160*. For some reason it always heats the water 20* less than the setting on the temp control box. I checked the water temp coming into the house and sure enough, It is 20* cooler than the set point on controller. I'm confused. Any thoughts?
 

leon

Minister of Fire
If the high limit safety temperature is 15 degrees+- to cut in at 170 and dump heat at 170 and it will cut out at 150
Well I got a first time fire lit today in the new wood boiler. It took about 5 1/2 hours to get the water temp to 135*. I have the set point set at 170*. When my OWB water got to about 130*, the gas boiler quit flaming on and it setting into circulating water only into my radiant floor zones. We are excited to get this boiler going. So far I haven't had to change any settings. That's good cause I wouldn't know how. I do have a question though, should I purchase a chimney cap to keep rain and such out? Also how often will I be adding water to the OWB?

=====================================================================================================


A rain cap is an option but you may need a chimney pipe extension too.

Hpw is the boiler filled ??? with a hose or a a Tee'd in line from the potable
water with a ball valve and Back Flow Preventer???

Is your forest eater equipped with a float valve and gallon marker tube with a sight gauge????
 
Last edited:

maple1

Minister of Fire
Sep 15, 2011
9,868
2,085
803
Nova Scotia
I think I would be asking the dealer you got the boiler from most of these questions.

We don't even know what kind of boiler it is or exactly what it has for controls.

5.5 hours to get it to 135 seems like way too long. I brought my 700 gallons from 60 to 160 on Monday in that time, or less. Is there boiler return temp protection in place?
 
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timberframe

Member
Dec 11, 2013
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Mid Michigan
If the high limit safety temperature is 15 degrees+- to cut in at 170 and dump heat at 170 and it will cut out at 150



=====================================================================================================


A rain cap is an option but you may need a chimney pipe extension too.

Hpw is the boiler filled ??? with a hose or a a Tee'd in line from the potable
water with a ball valve and Back Flow Preventer???

Is your forest eater equipped with a float valve and gallon marker tube with a sight gauge????
The OWB is a locally homemade boiler. It seems to be well built. In regard to the water filler pipe, It has a one inch filler pipe at the top for water filling. Maybe they make a drop-in float for that. I fill it with a garden hose.
How will I know if I need a chimney pipe extension?
 

leon

Minister of Fire
About your forest eater,

Do you know what type of steel they used to construct it with or the type of welding was done
to assemble it? How was the boiler pressure tested for leaks?

If all they have is a one inch filler pipe your going to have issues as you will not know how much water
your boiler is going to have in it at all times. I would strongly recommend that you install a muffler rain cap like the ones
used on exhaust stacks on tractors and construction equipment.

You have to make sure you have a very high high quality garden hose and keep it
inside at all times to prevent any water from freezing up.

A chimney extension and cap would be needed if the boilers flue is subject to down drafts or high winds affecting the boilers burn rate






I hope it works for you.
 

mike van

Feeling the Heat
Apr 24, 2013
359
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Kent Ct
Tframe - Can you post some pictures of your setup? How many gallons of water in the boiler? 5.5 hours seems way too long to get to temp. I fired up my Garn last week 1000 gals of, water was 62f, it went to 130 & tripped on the circulators in under an hour. Is the setup open system or pressure? Either way, you should not have to add water unless you have a leak or are boiling it off -
 

timberframe

Member
Dec 11, 2013
48
2
38
Mid Michigan
Tframe - Can you post some pictures of your setup? How many gallons of water in the boiler? 5.5 hours seems way too long to get to temp. I fired up my Garn last week 1000 gals of, water was 62f, it went to 130 & tripped on the circulators in under an hour. Is the setup open system or pressure? Either way, you should not have to add water unless you have a leak or are boiling it off -
The water jacket holds 125 gallons. It hasn't been very cold yet but all five of my radiant floor zones have been calling for occasional hot water. I only seem to need to fill with wood once a day so far. If it ever quits raining, I will shoot some pics.
My only concern and its not really a problem is: The OWB came with a ranco single stage electronic temperature control box. It functions good but it always heats the water to 20* cooler than what its set at. If I set it at 170*, it heats water to 150*.. If I set it at 180*, it heats to 160* and so on.
I know the unit isn't as nice as the factory built units, but it will pay for itself in a year or so. So far I'm very happy with it.
 
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timberframe

Member
Dec 11, 2013
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Mid Michigan
Here are a few pics.... I don't have the pipes wrapped with insulation yet in the mechanical room.
 

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timberframe

Member
Dec 11, 2013
48
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Mid Michigan
One of the neat things is that I have a Amish sawmill 1/4 mile from our house. I hauled 12 bundles of poplar slabwood with a tractor in a couple hours. Cost was 60.00 for 12 of them. That beats cutting wood.
 
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mike van

Feeling the Heat
Apr 24, 2013
359
139
303
Kent Ct
Two things that jump right out at me - your unit is way too close to the house, I hope it doesn't smoke/smell you out on some days. And, with wet undried poplar slabs, you will never get a real smokeless hot fire. I hope you have some better dryer wood for 'dead of winter' or you'll have issues heating a house that big. Hope i'm wrong, but that wood is awful fuel.
 

timberframe

Member
Dec 11, 2013
48
2
38
Mid Michigan
Two things that jump right out at me - your unit is way too close to the house, I hope it doesn't smoke/smell you out on some days. And, with wet undried poplar slabs, you will never get a real smokeless hot fire. I hope you have some better dryer wood for 'dead of winter' or you'll have issues heating a house that big. Hope i'm wrong, but that wood is awful fuel.
Hi Mike, The OWB has been chugging away for about three weeks now. I believe you are right in regard to how close the boiler is to the house. When we get a east wind, we smell wood. I guess it comes in through the roof overhand which is probably vented. I'm wondering if a long stove pipe would help, or if I should just move the boiler 50 more feet away from house for a total of 65 feet.
In regard to the slabwood, so far it has not been a problem. But its only getting down to 40* or so at night. We shall see what happens when it gets cold.
 

timberframe

Member
Dec 11, 2013
48
2
38
Mid Michigan
Here's a update on the homemade boiler.
Once I realized that I needed to shut off the gas boiler outside temp sensor, the gas boiler quit coming on. That was nice. I then turned the gas boiler down to 140*. So if I sleep in (Which has been known to happen), the gas boiler will come on if the OWB gets cold.
The OWB has worked well. It makes hot water for household use and keeps the house warm. I did have to put a new door blower on. It had gotten saturated with creosote and died from burning 18 bundles (Cord?) of poplar slab wood. I just switched yesterday over to hardwood slabwood. So far I like that better. I will probably move the boiler 50 foot farther away from the house in the spring. That will hopefully get rid of the wood smell that comes into house through the vents. I'm hopeful to get my hardwood slabwood purchased for next winter soon. It would be nice to get it drying. Should the slabwood be stacked or can I just make a looong pile on the ground? Seems like if I stack it, it would be stacked pretty tight and not get much airflow.
Do I need to be concerned about the creosote buildup on the inside of OWB? Hopefully it will burn off now that I switched to burning hardwood. Thanks for any insight that you may add.
 

mike van

Feeling the Heat
Apr 24, 2013
359
139
303
Kent Ct
Short story - I make syrup, about 150 taps now - I burn all my pine, hemlock, etc slabs in the evaporator, 2 to 3 full cords now. These are cut to 2' lengths early spring & sit covered on top only where the sun & summer wind get to them. One year sap ran a little longer, I had to get a bundle that hadn't been made up yet. Wet leaves, even a little snow still in there. Result was I couldn't keep the boil going in the evaporator worth a darn, after a few attempts, I quit that season. There is no creosote in the evaporator with dry slabs, nor in the chimney., never had to clean the pipe or chimney in 20 years. To get real heat, you need dry wood - My experience =
 

E Yoder

Feeling the Heat
Jan 27, 2017
294
48
303
Floyd, VA
I would agree with moving the furnace further away rather than extending the chimney. Tall chimneys will tend to plug with a regular updrafter like that.
Creosote in the blower is not normal. Might be a change needed there to prevent condensation running back in. And condensation in the firebox area on colder surfaces (chimney, door jambs) can eat out mild steel. Dry wood is a must.
The slow response time (heating up) may be part of the creosote problem. Undersized draft blower will slow burn with lots of moisture. Air leakage during off-cycles can be a source of creosote too. Even poplar slabs should burn dry with just a thin film of creosote.
A difference in temp readings between ranco control and temp dial could be inadequate flow rates or a design that doesn't push water through the furnace evenly. Could cause it to boil and yet pump low temp water. I saw a homemade unit like that once that the builder just didn't extend the return pipe to the far end of the water jacket. Boiled and circulated cool water. Drove him nuts.
Just some ideas. Enjoy your wood heat!
 

timberframe

Member
Dec 11, 2013
48
2
38
Mid Michigan
Thanks guys for the info. Today was very windy here in Michigan. My two sections of pipe extension (10') blew down. The pipes had lots of creosote in them. About half full. One of the pipes had burnt through close to the boiler. Tomorrow I will buy a new 5' pipe and install. I am still getting a lot of creosote in the door blower. Hopefully with dry wood next year, that will help the problem.
 

E Yoder

Feeling the Heat
Jan 27, 2017
294
48
303
Floyd, VA
It might be worth getting stainless chimney pipe. Then it'll last.
 

E Yoder

Feeling the Heat
Jan 27, 2017
294
48
303
Floyd, VA
I had some 304 SS pipe made for our customers to use. Never saw one burn out. I dunno.
 

timberframe

Member
Dec 11, 2013
48
2
38
Mid Michigan
I was thinking about moving the boiler away from house. How far would be a reasonable distance to get the OWB away from our house?
 

E Yoder

Feeling the Heat
Jan 27, 2017
294
48
303
Floyd, VA
I'd do somewhere between 50-100' depending on wind direction. We've pumped up to 300' but flow rates get really low on 1" Pex.