Is oil-fired boiler more effective for steam than gas-fired?

Westport_Johnny

Hi, Newbie here.  Looking for some independent guidance.

Bought a 175 year old 3300sf house in 2007.  Discovered that old (60 plus yrs) oil-fired boiler with hot water coil was not working in Oct 2007, when it was cold.  Family needed heat & hot water asap.

Have Nat Gas hookup at the house for kitchen, and looked into getting a gas-fired system installed.  Unfortunately, in CT the utility company does not sell and install systems- only deliver the fuel.  Called numerous contractors with little or no response- for sure, none recognized the urgency.  Ended up calling a large local Oil company that took care of everything right away.

Been very pleased with the equipment (Smith boiler and Toyotomi tankless direct fired hot water heater), and the service (very responsive to any and all issues). Alas, oil fuel and service contracts are expensive... we use over 1700 gallons per year.

Figured that while the Smith oil-fired steam boiler is only 4 yrs old, with Nat Gas being about half the cost of oil per BTU the payback on a Weil McLain or Burnham gas-fired steam boiler would only take around 3 yrs.  For me, that's worth changing.

The question I have is, even with similarly sized & efficient systems, will I be sacrificing performance?  I was told by an oil company which does some gas systems on the side that oil burns hotter, will heat the house faster, will provide greater comfort, and since I'll burn more gas for similar results, the savings would be minimal.

I'm skeptical as I figured a BTU is a BTU, and while I will use more gas, the effective cost to heat my house would be much less (e.g., Nat Gas Therm 1/3rd the cost of a gallon of Heating oil, but 70% of the BTU's, so savings would be about 1/2 for similar output).

Can anyone confirm whether gas-fired boiler used for steam heating would provide similar effectiveness as an oil-fired boiler?  Or is it true that oil-fired works better, and we'll be sacrificing performance?

Many thanks,

John

Steamhead

If this is a Smith 8 series boiler

it'll run fine with a Carlin EZ-Gas. We install them this way from scratch, as the thermal efficiency of this setup is about 6% better than the usual atmospheric gas steamer. This way, you can convert without buying a new boiler.



Note that the 8 series has two ratings for each model on oil, L (low) and H (high). The gas burner setup only uses the lower ratings. We'd have to see which rating the oil company used.

Westport_Johnny

Yes, its a Smith 8-S-5

Very interesting!!! (sent a msg to you direct, too).

Yes, its a Smith Series 8 (8-S-5), which at least originally had a Carlin oil burner (might have been swapped out since then, but for sure its a Smith that when initially installed had a Carlin).

Aware of the high & low outputs / not sure how its set.  I now presume that with my question on effectiveness, it will depend on setting (big difference if on high with 152 MBH vs. low with 126 MBH... my guess is that its on low, as the initial quote was for AFUE rating of 86.2%... which actually looks like the rating for 8-W-5L; the 8-S-5L is 85.3%)

Anyhow, if the job can be done by only moving gas to unit, swapping out the burner, and if necessary addressing chimney lining, that would be prefered (as the Smith is good equipment / hate to idle a 4 yr old boiler, and figure I'd save a few $$$ too).

Hope to learn more about Carlin EZ-Gas

Again, thanks!

John

Rod

Wet Based Boiler with Gas Power Burner

Hi John- It sounds as though you have really lucked out as Smith approves that model boiler for gas,  It's a wet based boiler (most oil boilers are) and it is VERY efficient with a power gas burner installed. On a wet based boiler the combustion chamber is surrounded by water where as on the normal atmospheric gas boiler the boiler is positioned over the burner sort of like a pot of water on a gas stove. (See attached drawing)

"Steamhead" is a very experienced steam pro who has done a lot of these installations so you are getting excellent advice there.



I might mention if you are new to steam there are some good books available in the Shop section of this website. i would recommend "We Got Steam Heat!"

http://www.heatinghelp.com/products/Steam-Heating-Books/25/61/We-Got-Steam-Heat-A-Homeowners-Guide-to-Peaceful-Coexistence

and "The Lost  Art of Steam Heating"

http://www.heatinghelp.com/products/Steam-Heating-Books/25/68/Lost-Art-Of-Steam-Heating

These books are written for someone new to steam and are easy humorous reading.  They are packed full of facts and diagrams of how your steam system works and what you can do to make it run more efficiently and economically. They have saved me their cost at least 100 times over.

- Rod

Westport_Johnny

Yes, feeling fortunate :-)

Thanks Rod.  Great to hear that I might have gotten lucky selecting the Smith Series 8 a few yrs ago.  And also thanks for the link to the books... I just discovered this site tonight, and along the way heard about the writer and those books... unfortunately the links to the book on elsewhere on heatinghelp.com (right side of page) were dead.  Will definitely order.



And absolutely "Steamhead" (Frank) knows his stuff.  Read a few of his posts and he's consistently helpful (as well as funny- liked reading about a "Snowball" replacement).



The challenge I have is where to turn to next... looks like Steamhead is in MD while I'm in CT.  Would like to engage a contractor with his level of knowledge and care- unfortunately, not too many of those around.  In fact, not familiar with any steam / plumbing guys in this area (again, I've looked at gas almost annual since 2007 and haven't had anyone to work with).  I understand I need a professional to do the work, whether swap out the Smith's Carlin burner with a Carlin EZ Gas burner, bring gas over to the boiler & connect, shut down the oil line (without cutting oil connection to the Toyotomi hot water heater, which I'll keep active), address any required changes in attachments from boiler to the chimney, address chimney lining if necessary, etc. etc. etc.



If anyone has suggestions on where I should turn, let me know.  Otherwise, may have to call Carlin EZ Gas distributors in CT and ask them for some recommendations.



So far, lots of great guidance- in fact, a sound recommendation.  Only need to find out how to execute.  Anyhow, a successful evening... maybe tomorrow we get closer to the solution.



Many thanks to all.

Steamhead

If you know the nozzle size

and pump pressure being used in your oil burner, that will tell us if it's set up for high or low.



On the 5-section boiler, assuming a pump pressure of 100 PSI, a 1.35 nozzle is used for the low rating. A 1.65 nozzle is used for the high rating. These ratings are in gallons per hour at 100 PSI.



Some Carlin burners specified a pump pressure of 150 PSI. In this case a 1.10 nozzle would be low rating (actual rate 1.35) and a 1.35 would be high rating (actual rate 1.65).



Also, you'd have to change the barometric draft regulator (swinging disc on chimney connector) to a double-swing type which is proper for gas, and add a blocked-flue safety switch to the new barometric. These are standard items, needed to meet Code.

Westport_Johnny

Confirmed PSI setting & nozzle size

Hi.  Confirmed that my Smith Series 8-S-5 has 150 PSI with 110 size nozzle; so its currently set up at the low setting (which I presume is a good thing since a conversion / retrofit for Carlin EZ Gas burner would be done at low).

I really appreciate the guidance provided; clear on need to move gas over to boiler, a Carlin gas burner, as we;; as barometric draft regulator, blocked flue safety switch, perhaps some chimney cleaning / lining, and who knows what else.... having an old house, there's always more surprises.

At this point I wonder if you have any additional insights?  Can you recommend anyone to do the job, or should I start looking a "Steam Guy" in Fairfield County CT?

Recommendations to how to make it happen are welcome- unfortunately it seems like Steam Guys are a rare breed, close to extinct in these parts.

- John

Steamhead

Try

the Find a Contractor page of this site. That area should have plenty. I know "Charlie from WMass" works with EZ-Gas burners a lot, not sure if he comes that far though. 

Rod

Gas Conversion

Hi John-

   Just some thoughts-  While it would be obviously beneficial to get a steam pro to do the conversion, since they are only dealing with the burner side of the installation,  all you really need is a good burner guy, preferably one that is familiar with Carlin Gas burners. Since there are a lot of Hot Water systems around that shouldn't be too much of a problem to find a good burner guy.

I’m in a similar situation in that I don’t have a good steam pro near me (rural Maine) but I do have a tech who is great with oil burners and HW, but really doesn’t understand steam. We have an agreement - he does the burner side and I do the steam and this  works out great!

You want a pro that has the equipment to take digital combustion samplings / readings which any real burner man should possess. ( Ask him to give you the final printed read out and save it for future comparison)

You might want to contact Smith and ask them to email you a printed copy of the recommended burner settings for that model boiler with a Carlin EZ gas burner installed as that would probably reassure / be of help to your burner installer. (Steamhead, I'm sure would give you some advice on this also.)



Gas Company- You might want to check the gas requirements of the Carlin burner and then check with the gas company to be sure you have a gas line large enough to supply the boiler. If a cost is involved you might be able to get some of the cost defrayed as the gas company may have credits available for switching over to gas heating.



Chimney- You most probably will have to get  your chimney lined. Try http://www.ncsg.org/ which is the Chimney Sweep organization as a possible lead to someone who does liners.  Also look at old postings in the “Search the Wall” function as there has been a lot written on chimney liners. The good burner man you find will probably be knowledgeable on liners. Get a good quality one - not aluminum.



On the steam side-  Since you have ordered “the Books” they will be able to tell you all you need to know about steam and the guys on the Wall will be happy to answer any questions you have.

- Rod

Westport_Johnny

Instead of converting, worth adding separate Gas system?

Rod- Thanks for the good advice on locating a supplier, as well as learning optimal settings for the Smith.  The conversion recommendation from Steamhead was excellent.

Interestingly enough, I found no CT based heating companies under "Find a Contractor" link on the banner at top of this page.  Fortunately I located 2 options- I was aware of an local old-pro plumber who partners with a boiler guy, and today I connected with a real, live "Steam Guy".

   - The first option, which had already given me a reasonable estimate on a new Weil McLain, came back with a reasonable estimate on the Smith conversion. 

   - The second guy, who I only discovered in last 24 hrs, will come by to see the job next week

Between the two, I think I'm in good hands.

Anyhow, something else has come up today... before my 1st post in this thread, when I met with the plumber / boiler team, I casually raised the concept of having "dual systems", the existing oil-fired system + a new gas-fired system next to it, with the option of manually switching between heating sources.  Not sure if it was feasible, or let alone practical (as primary reason for looking to gas was to save on fuel bills, and with the differential today not sure oil system would get much use), but figured I'd toss out the idea.

Well, I spoke with those plumber / boiler team this evening to alert them to the change of plans (convert the Smith Series 8 using a Carlin EZ Gas), which they understood and confirmed he can do, but at the end of the call they asked whether the dual system idea was now dead.  Apparently, the estimate they gave me for the Weil McLain assumed keeping the Smith in place and available- I totally forgot / gave up on that concept, assuming that having 2 systems was not feasible and Smith was going to be hauled away.

I wonder, is anyone familiar with a residence having both gas & oil-fired steam systems, with capability to switch between the two?  Is it possible?  Reasonably efficient?  Worth a few K's for a homeowner to have the option to select heat source?

Figure that since I found this forum and had such great success in getting excellent insights, I might as well ask this question to see if anyone has knowledge to share.

Many thanks!

Tim McElwain

It is really not feasible to have two boiler systems

however I would make sure to keep the oil burner set aside  and also the single swing barometric from the oil. That way if you want to switch back later you can.



By the way properly set up you will with the Carlin EZ gas power burner get very good efficiency at least equal to or exceeding the oil. It also will not need an annual cleaning. It should however be serviced once a year at least.



Carlin will by the way ship a burner to your contractor all set up for your boiler at the proper firing rate.



There are at present no residential dual fuel burners (just commercial) I wish someone would make one though for residential purposes OH well I can dream.



I wish you well and you will not be sorry, I have installed over 3,500 conversion burners in my career and have had very few problems with any of them.

Westport_Johnny

Another good reco on Conversion from oil to gas fired steam

Tim, Very clear / thanks.  Probably best to keep in simple.

So, at this point, unless someone else chimes in with input, is to 1) contact Smith to learn the recommended burner settings for Series 8-S-5 using a Carlin EZ gas burner, 2) sort out the contractor (s), and then 3) coordinate burner order from Carlin with the contractor so that we get the right model, preset the burner to the right firing rate using specs from Smith.

Much appreciated- this forum has been terrific.

- John

Steamhead

Actually

you would get the burner from Carlin, not Smith. They have the specs in their "OEM Spec Guide" which your contractor should have. If he doesn't, he can get it from Carlin. 

Ex Maine Doug

Why not two boilers

One gas and one oil.  I don't see why your idea of two boilers side by side won't work. it is not an issue of the plumbing part, people have multi-boilers to meet variable demand.  Some careful exhaust stack work would need to be done to handle the draft requirements.

Our town in ME might be gas piped next year and I plan on converting both boilers to gas and keep the oil burners. Whatever BTU is less costly will determine which fuel is used. I could just convert one boiler but at 10 degrees I need both to run.

In your case you are thinking of two boilers of the same size and that only one is needed at a time.  Should be doable.

Westport_Johnny

Carlin settings

Yes, I understand the gas burner comes from carlin (interestingly, per their website, looks like need to get from a distributor- if so, who would preset???)

I figured I'd call Smith only to learn their recommended settings.

If carlin knows what's appropriate for a series 8-S-5 and there's no need to research with Smith, that's even easier!



Thanks

Westport_Johnny

While feasible, perhaps not really needed

Thanks for the input Doug.  You may be right that its physically possible.  However, I guess the question I should have asked myself is why?

- My region gets cold, however Southern New England is closer climate wise to Mid-Atlantic than Northern ME / Nova Scotia so dual system and / or secondary back is not critical.

- Already have built-in backups (this old house has 6 fireplaces, so in we could supplement heating system when on, and have a fallback in event of system failure) 

- Arbitrage on commodity isn't going to be productive; I do realize that we're probably be better off putting the $$$ into insulation.

In the end I think its best that, at least in my case, we keep things simple and go with the conversion recommendation provided by the knowledgeable community members.

John

Ex Maine Doug

I hope we get the gas mains in

I will be one street off but an easy straight shot across a partial alley. I will be happy to give up the annual process and cost of cleaning the junk out of the boilers left by burning oil. My boilers are direct vent so we get the soot and stink outside in my parking area.

The 174 mega-watt Co-gen plant nearby has the high pressure main line from which a low pressure line will be extended into town, we hope soon.

Let us know how your burner conversion works out.

Tim McElwain

Westport what is you location

is it Westport Mass? If so I am nearby in RI at my training center in Warren RI. Give me a call and we can connect up and I can help answer anymore questions you may have. My e-mail is gastc@cox.net and my phone is 401-437-0557, look forward to hearing from you.

Westport_Johnny

Nope- Westport CT

Tim, thanks for the offer, but unfortunately further away.

In Westport CT, not Westport MA.

(Not the first time that's happenned.  Very familiar with the region; we keep a summer home in South Kingstown RI near Narragansett, and drive right through the area each summer when we go out to visit our older girls on the Cape.)



Too bad its not a good fit.



John

Westport_Johnny

Smith S8 Setting for Carlin EZGas

Thanks for the suggestion... sent a note to Smith, noting I had an oil-fired EZ Pro burner, and wanted to swich to gas-fired EZ Gas burner.

Kind folks quickly sent a me a scan of the settings for all Series 89, (which I am trying to attach here... if it gets loaded, my particular need is boxed)

Everything moving along, although somneone's raised a concern that the town may not allow me to continue using my oil fired Toyotomi Hot Water with a separate Nat Gas boiler going up the same chimney.

We shall see

Tim McElwain

Gas and oil can use

the same chimney as long as code is follwed as to placement into the chimney. Check your local code. Some say gas above oil others say smaller above the larger input.

Sparrow

Fairfield Cty Help

Hey Johnny,



I live in Fairfield county as well. and i work for a local supply house for the last 13 years. the best plumber, heating and a/c guys i know are Ed DeBrito and B&C Heating, both are out of Danbury. These guys really know there stuff!!! Good Luck

Westport_Johnny

Update on Conversion Process- Chimney Code

Folks- wanted to share an update on the oil to gas conversion....

While all's moved along well with respect to preparing for conversion (chimney inspection, cleaning & lining needs, finding contractor to bring gas pipes over to boiler / swap burner / double swing barometric draft regulator / blocked flue safety switch), the project hit a snag.

As noted earlier in this thread, was hoping move to gas heat using my Smith Series 8 steam boiler while keeping my high efficiency direct fired oil tankless hot water heater.

Checked with building dept and was advised that CT state code does not allow for 2 different fuels up the same flue.

So, I guess, in the absence of direct vent for the hot water heater (not sure it can be done), I'd be looking at abandoning oil all together (writing off the wonderful Toyotomi O-M 180 HW system, removing it from the basement, as well as I guess removing the above ground oil tank + writing off the hundreds of gallons stored), and either a) adding the optional Smith tankless heater for HW, which supposedly gives up to 5 gallons per minute, or b) adding a separate gas HW heater.



Any clues on whether the Toyotomi HW system can be direct vented (yes- I'll research myself), or input on optional Smith tankless HW works reasonably well? 

As always, insights appreciated.



John

Steamhead

Go with an indirect

we like the SuperStor for use with steam boilers. Here's a link to a thread, with pics, where we installed a SuperStor with a Smith 8:



http://www.heatinghelp.com/forum-thread/132567/One-of-the-worst-maintained-oil-fired-boilers-weve-seen

Westport_Johnny

2nd Update: Oil to Gas Conversion

Did a bit of research, and went back to the Building Dept citing IRC 2427.5.6.2 and NFPA 211 9.8.3, both of which declare that running 2 different non-solid fuel appliances (e.g. Oil & Gas) up the same flue is permitted.

Building Dept recognized this and changed its stance / corrected its error and will now let me go ahead with the conversion.  With that, can keep my nice high efficiency oil HWH and avoid having to spend $ on a new gas HWH.

(Also learned that the Toyotomi OM-180 that we have cab be direct vented, however even if I wanted to move it, the fact house perimeter is surrounded by a porch its not really possible).

So at this point we will proceed.  Moving on getting a permit then chimney work done (stainless lining; will need to enable 2 separate connections), gas line plumbing, and burner conversion (change from Carlin EZ Pro oil-fired to EZ Gas, addition of double swing barometric draft regulator + blocked flue safety switch).  Will also call the gas Company, which apparently will change my service status (move to a lower heating rate), as well as provide a rebate on the gas burner (which is nice).

Key is to get the chimney addressed asap, as the rest can be done pretty quickly.  Unfortunately, as those guys are busy, booked out a couple of weeks, I must wait. Once its done, probably early Nov, I'll share any other learnings. 

Appreciate all the guidance provided by members in the community- thank you!

Paul Fredricks_3

Great

Great news on the chimney. They do get ideas at the building department that may not be correct. You handled that well.



And a great idea to hang onto the existing burner. Just put it on a shelf. When and if the day comes when oil is cheaper than gas, you can always switch back.



Just so you other guys know, we are his current oil company. I'll be interested to see how this conversion turns out, from an economy standpoint. Hopefully good for John.

Westport_Johnny

Chimney connection may be an insurmountable problem

Paul, Thanks for chiming in.  Yes, when I called Dom G. at the building dept this morning he heard my earlier message, he started off reading that it is in fact permitted (he noted he was thinking of a solid fuel appliance, which cannot be combined with gas or oil appliances).

Actually had a chimney expert here a few minutes ago, who coincidentally was the chimney guy for the previous owners, and has worked on this house for the past 20+ years.  Had good news and bad news...

- chimney is already lined, so that's set, however.

- bad news: base of chimney, where boiler / hot water come in probably cannot accommodate 2 separate pipes. (Detached the vent from hole in masonry and looks like the fuel flue is 1 pipe... not sure it can be converted to take both a smaller gas exhaust above a larger oil exhaust).

Not giving up yet, but will need to have someone else to look at it; if that's the case, will either have to stay all oil (which while expensive, is terrific- I do like how it works, and love your company's service, which is outstanding), or go all gas.

More to come later....

 

Tim McElwain

Why not connect them

at the connector prior to entry into the chimney. That is acceptable as long as the connector is rated for oil. Any gas system can be flued into an oil designed flue but oil has to be heavier grade of metal than that allowed for gas.



I was surprised when I read your earlier post about not allowing the two fuels into the same chimney, glad that got straightened out.

Westport_Johnny

Vent connector idea

Tim- sounds nice, but unfortunately having a hard time visualizing how the connector would work (with 2 separate vents going in... presumably 6" gas flue above, 8" oil flue below).  

Any ideas where I can see such a thing? Or better yet, know any suppliers who sell such a kit?

Westport_Johnny

Nevermind- plumber already assumed the connector

Tim- thanks... don't need a visual on the connector... confirmed with my plumber, who was going to do the piping, burner swap, etc. that his quote alreay assumed using a dual vent connector to the flue when he gave me the quote.

So, in the end, as the fuel exhaust flue was deemed clean and lined, looks like we're moving ahead next week.

Excellent / very happy.  Will post an update after its done in next 10 days.

Paul Fredricks_3

wait

The vent connector that's there now should work fine, I think. It should be hooked up the same way as the oil boiler and water heater, just need the different gas type damper.



Post a picture if you can. It's a Y connector at the moment.

Westport_Johnny

Current Set-up (single flue openning)

Paul- Yes, as you know, the current set up is a Y connection from Toyotomi OM-180 oil-fired hot water heater (on left) and Smith Series 8 oil-fired boiler (on right).... both appliances going into a single openning.  A moderate-quality picture from my phone below. 

I am not quite sure what Tim was referring to / how the connector that goes through the masonry and connects to the single chimney flue openning (to my untrained eye it looked like a big 'ol black stove pipe), but my plumber seemed to know.

While I appreciate that 2 separate opennings would be preferred, I am working with the understnading that the oil and gas appliances can be connected and use a single flue openning.

Anyhow, moving forward with Tim's suggestion, I'm guessing that it what is needed is a Type L vent (suitable for oil and gas) that accepts the exhaust differently that what's there right now... that is, instead of a Y connection like I have today, a wider / lower connection for the oil-fueled Toyotomi and a narrower/ higher connection for the gas-fired.

By the way Paul, as the provider of both the Smith and Toyotomi, let me ask you something... am I correct in thinking the gas-fired Smith boiler will have the lower BTUH input (which should use the narrower pipe and be positioned at a higher point), and the oil-fired Toyotomi hot water will have the larger BTUH input (which would use the wider pipe and positioned a lower point)?

Many thanks to all!

Paul Fredricks_3

no

The Smith, if I am reading this right, is fired at 1.35 GPH (low input rate) and should be about 190,000 BTU input. I guess that's the same with a gas burner. The Toyotomi's input is about 1.05 GPH, or 148,000 BTU's.



I don't understand the need for type L vent pipe. There is no problem with clearance to combustibles. I think the current vent set up is correct, except for the damper installation for the gas.

Westport_Johnny

Separate oil & gas appliance connection into single flue openning

Paul- Thanks.  Coincidentally spoke to Don C this afternoon (left him a message a few days ago- didn't realize he typically works remote).  He essentially said the same thing- that the existing Y connection, which is rated for oil, should be fine. 

I do find it odd as it contradicts the "gas above oil" and "lower BTU input using narrower pipe positioned above, higher BTU input using wider pipe positioned below)... I guess that it doesn't matter / the rule only applies when connecting into 2 openings

Anyhow, if it was relevant- again, I presume its not, in our case the placement would be opposite, with oil above gas... the oil-fired hot water is the lower BTU appliance and would be positioned in the top slot, and the gas-fired boiler higher BTU positioned in the lower slot.

Again, grateful for the outstanding guidance from everyone in the community, welcome any other insight people can add, and definitely plan to post an update when complete

Tim McElwain

Paul my concern is due

to several jobs I have been on recently with a conversion over to a gas power burner.Three were with the Carlin EZ and two with the Midco EC. They have been in a little over two years. They also installed gas storage water heaters with these and connected the system to existing oil system vent. The issue is on all five of these the connector pipes are heavily corroded. I am concerned that due to increased wet-time on the gas equipment the condensate is corroding these pipes. I have one other job that was converted at about the same time as these and we used a Type L vent connector due to the length of lateral run and it is fine and actually has a worse venting situation than the other five jobs. All five of those jobs tested out with high combustion efficiency above 81%. The water heaters are all FVIR units and I am having some problems with some of them anyway.



Perhaps this job will be okay seeing you have an oil system for hot water and gas power conversion for the heating boiler.



I was just trying to lean toward prevention ahead of time.

Westport_Johnny

Type L vent connector

Tim- thanks for coming back with additional insight.  agree that replacing the connector with something new is fine... cost not significant, and an ounce of protection...

A question...  if I understand correctly, Type L refers to the structure, with difference vs. Type B  being a stainless inner wall used for Type L....

Question is, for a single flue entry, should I expect it to look like my current Y connector (with both gas and oil fired exhausts coming in on same plane), or need the design accommodate an "upper" and "lower" position???

As always, your expert advise is much appreciated,

John

Westport_Johnny

Type L vent connector

Tim- thanks for coming back with additional insight.  agree that replacing the connector with something new is fine... cost not significant, and an ounce of protection...

A question...  if I understand correctly, Type L refers to the structure, with difference vs. Type B  being a stainless inner wall used for Type L....

Question is, for a single flue entry, should I expect it to look like my current Y connector (with both gas and oil fired exhausts coming in on same plane), or need the design accommodate an "upper" and "lower" position???

As always, your expert advise is much appreciated,

John

Tim McElwain

Your contractor

should use the "L" with stainless steel inner liner versus "B" vent which I do not like with gas conversions and also you can't use "B" vent with oil.



Yes it should come in the same configuration as the existing entry pipe into the chimney.



The issues now days with all of the increased efficiencies with both gas and oil in the 80 + range it takes longer to get Delta "T" (temperature difference) adequate to get a good draft. Draft is created by height and temperature difference. If we lose temperature in the connector before it goes into the chimney then "wet-time" is increased. You are looking at two different appliances both with barometric draft regulators and the gas being double swing in conjunction with the oil single wing can also be an issue if flue losses are not reduced all the way from the appliances to the chimney.



By the way at roughly one year from now your chimney will need cleaned again as it will develop a lot of fly ash from the acidity of the gas scrubbing the inside of the chimney along with the increased vapor content.

Paul Fredricks_3

Tim

I still don't see the advantage of the L type. I understand the wet time and the possibility of condensation. Are you talking all the vent pipe, right from the unit, or just where the Y is? If at the Y and into the chimney, it's only about 3' of pipe. Seems like a waste of time. And the oil fired water heater would be a help since the stack temp of those units is typically 450 - 500°.



Hadn't heard about needing the chimney cleaned a year later. Is that just after the first year, or every year?

Tim McElwain

The most critical point is at the

connector to common vent location. This is usually the location of initial extreme wet-time so only a heavy duty vent connector not the entire liner. If I remember this posting his contractor found that his chimney is already lined (clay tile I assume). That should be fine for now.



The cleaning issue is on any chimney and boiler conversion after the first year of operation on gas. The oil residue in the boiler (even after a good cleaning) and in the chimney will cause a fly ash to be formed and accumulate on the boiler surfaces and also fall down into the clean-out area of the chimney. I have gone back one year after conversion and found the fly ash accumulation all the way up to the flue pipe entry into the chimney. I have had a policy on all the conversions I have ever done to include in the cost of the install a one year cleaning. This fly ash by the way has great insulating ability so the efficiency of heat transfer from the combustion chamber and boiler sections is affected.

Paul Fredricks_3

Ahhh

Gotcha. Makes sense now. Thanks, Tim.