# Cold Start Oil Boiler, Chimney lining deterioration Questions



## peakbagger (Jun 18, 2012)

My parent had a new Buderus boiler put in five years ago. It was equipped with a Taco outdoor rest controller and "cold start". I believe that the unit only runs when there is demand for heat.

The boiler is piped into a standard single flue chimney with masonary full blocks on the outside. and stadard flue tile on the inside.  There isnt a chimney cap and the total from the boiler breech to the top of the chimney is approx 20 feet. Its an interior chimney built in the sixties. 

Their primary complaint is when it rains heavilly liquid leaks out from under the chimney base. It is foul stuff and looks and smells acidic. When I look into the clean out door, the tile looks deteriorated on the edges where the clean out opening was cut long ago.

I beleive I have seen reference and have heard from folks with similiar cold start boilers that this is possibility with a cold start oil unit as the exhaust gases are condensing in the chimney and forming sulfuric acid deposits. The normal solution I have heard is slip in a stainless steel liner set up for oil and install a stack cap. They asked about just putting a stack cap to keep the water out, but my personal experience is that can cause deteriation of the liner at the top of the chimney and the acid will still form.

Has anyone experienced this and how did you solve it? My father is 91 and my mother in her eighties so solid fuel is not an option. The depressing part is that there is natural gas line in the street but my mother refuses to allow gas in the house as the local gas utility had a long term reputation for houses blowing up (they currently have to replace most of their street piping due to leaks)


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## btuser (Jun 18, 2012)

If it just happens when it rains then I'd say try the cap.   That's a lot cheaper than any other option I can think of.


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## heat seeker (Jun 19, 2012)

Also suggest a cap. The flue never heats up enough to evaporate any water or liquids that get on the tiles. On a regullar furnace, the flue is usually warm enough to dry itself out. When rain gets in the flue, it's absorbed by the tiles (unless it's really excessive) and then gets evaporated over time. Your folks' flue may be gummed up so that it can't absorb any rain. It might be time for a chimney sweep to have a look-see.


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## Don2222 (Jun 22, 2012)

Hello

I also have a 60's inside chimney with a Buderus triple pass, cold start boiler with an outdoor reset. Now this boiler is NOT a condensing boiler and maintains a stack temperature of atleast 300 Deg F. So if you have a condensing boiler then I would recommend either a stainless steel chimney liner or a new stainless steel chimney run up beside the original chimney. That is what I did and now I use the stainless steel chimney for the boiler and the original block chimney for the Wood Pellet Stove.


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## fbelec (Jun 25, 2012)

i too would install a stainless steel cap. just make sure it is installed with stainless screws. seen a two year old cap fly because the screws were cheap. oil is very acidic. the difference in stack temp from a standard oil furnace and the budarus is about 100 degrees. should be ok in the heating season but not as hot as it should be in the summer when it's used for water. if you are getting lots of water after the cap you'll need to check out the adapter that is installed on the boiler to allow the smoke pipe to fit. budarus had a problem that they didn't want to admit to. right at the adapter or just inside there they leak a little and mostly but not all the time when it is hot. some of the leakers would not leak when cold. but you should be able to see it hot and a very small stain. hopefully you don't have a leaker because your plumber will have a fight on his hands. other than that they are a very nice boiler.


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## Don2222 (Jun 25, 2012)

fbelec said:


> i too would install a stainless steel cap. just make sure it is installed with stainless screws. seen a two year old cap fly because the screws were cheap. oil is very acidic. the difference in stack temp from a standard oil furnace and the budarus is about 100 degrees. should be ok in the heating season but not as hot as it should be in the summer when it's used for water. if you are getting lots of water after the cap you'll need to check out the adapter that is installed on the boiler to allow the smoke pipe to fit. budarus had a problem that they didn't want to admit to. right at the adapter or just inside there they leak a little and mostly but not all the time when it is hot. some of the leakers would not leak when cold. but you should be able to see it hot and a very small stain. hopefully you don't have a leaker because your plumber will have a fight on his hands. other than that they are a very nice boiler.


 
Hi fbelec

Where did you say the Buderus leaks? Is it where the yellow arrow points in the pics below?


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## fbelec (Jun 25, 2012)

yes. take off the smoke pipe and look inside with a bright light. i help with the install of these boilers and wire the computers to control them. i liked the budarus. it heats quick which saves money along with the efficiency


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## fbelec (Jun 25, 2012)

also take off or move out of the way if you can the back jacket of the boiler to check the rear cast of the boiler.


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## Don2222 (Jun 25, 2012)

fbelec said:


> yes. take off the smoke pipe and look inside with a bright light. i help with the install of these boilers and wire the computers to control them. i liked the budarus. it heats quick which saves money along with the efficiency


 
*I just took the flue screw out and removed the flue pipe and took a pic. Does it look ok? I do not see any rust?*

Thanks for mentioning this. I hired an independent boiler man to install this *110K BTU Buderus G115WS/4 Cast Iron Oil FHW Boiler.*

I helped with the 4 day - 12hr/day install. The SuperStor was already there!

It is a nice unit but you really have to know what you are doing to get it right!
Such as twisted pair wire to the outdoor reset so a comercial plane talking to the landing tower does not cause false signals! Also a 12" copper heat loop out of the Superstor DHW output so you do not loose heat at night by convection thru all the hot water pipes in the house! The Superstor is not like the Electric DHW tanks that come with heat nipples already installed! Also the Buderus DHW tank is a nightmare and is NOT recommended!

In my case we added a Cold Water Line Expansion Tank so when the water is heated in the Superstore tank and expands, it pushes the cold water out the bottom into the expansion tank so no hot water is lost out the top! Saves Oil!

Then in my case in order to set the pressure on the bladder in the Cold Water Line Expansion tank, I had to add a water pressure regulator to the town water line coming into the house! The town water tank is located on a high hill for our development and we get 90-100 PSI from the town. The cold water expansion tank only goes up to 80 PSI ! So we set the pressure regulator to 55 psi for the incoming town water and the cold water expansion tank to 55 psi to match and it works!

This explains why the auto fill valve on the old boiler kept failing! 100 PSI at the input to go down to 15 PSI for the boiler system was a real strain on that poor valve!


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## Don2222 (Jun 25, 2012)

fbelec said:


> also take off or move out of the way if you can the back jacket of the boiler to check the rear cast of the boiler.


 
How do you do that?

From inside the door to the fire chamber?


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## Don2222 (Jun 25, 2012)

fbelec said:


> yes. take off the smoke pipe and look inside with a bright light. i help with the install of these boilers and wire the computers to control them. i liked the budarus. it heats quick which saves money along with the efficiency


 
Hello fblec

Just wondering what type of outdoor reset or computer controller you wire up to the Buderus Boiler?

I personally like the reasonably priced Tekmar 260 that when done heating a zone, it dumps any residual boiler heat into the DHW tank!
http://www.pexsupply.com/Tekmar-260-Boiler-Control-One-Stage-Boiler-DHW-4152000-p

Did you wire a Buderus Controller? If so then how does that work?


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