Condencing Boilers

[djblech]

I am looking at replacing my back-up boiler with a more efficient LP condencing boiler. If I ever sell this place, I can't count on the wood boiler being a selling point.( Most people don't want to work as hard as I do for heat IMO.) Does anyone know a website or company I can go to for info and $ for these boilers. I did a search and found some boilers that had on demand hot water heating capabilities built right in. I have a hot water maker running off 1 leg of my current boiler, is the on demand more efficient? I was thinking of doing the install myself as the old boiler is in place and working.
Thanks for any information.
Doug

 

[Reggie Dunlap]

Take a look at the Trinity boilers made by NTI. I've put them in a bunch of houses, including my own, with good results. They are wall mounted and direct vented in 4" PVC.

 

[henfruit]

try trinty boilers.

 

[huffdawg]

Pex supply has a good selection of high efficiency gas boilers, they are between $3500 and $5000. I have owned a Buderus for 2 years and it has been working great with no issues.

Huff

 

[Chris Hoskin]

I would suggest that the extra cost of a high efficiency modulating/condensing boiler is not worth the price - UNLESS you have a low temperature distribution system like radiant floor or panel radiators. If you have traditional hot water baseboard or radiators, or a normally sized hydro-air system, then your boiler is going to have to operate at 180 degrees in order to effectively heat your home. At those high temps, a mod/con is only operating at about 85% efficiency so you may as well save some money and put in a mid-efficiency boiler that is meant to run at higher temps and will deliver the same efficiency.

 

[DaveBP]

I would suggest that the extra cost of a high efficiency modulating/condensing boiler is not worth the price - UNLESS you have a low temperature distribution system like radiant floor or panel radiators. If you have traditional hot water baseboard or radiators, or a normally sized hydro-air system, then your boiler is going to have to operate at 180 degrees in order to effectively heat your home. At those high temps, a mod/con is only operating at about 85% efficiency so you may as well save some money and put in a mid-efficiency boiler that is meant to run at higher temps and will deliver the same efficiency.

This is vital to get the extra efficiency that you will pay so much more for. Don't count on online sellers to mention it.

Siegenthaler reminds his readers about it over and over.

 

[woodsmaster]

I would suggest that the extra cost of a high efficiency modulating/condensing boiler is not worth the price - UNLESS you have a low temperature distribution system like radiant floor or panel radiators. If you have traditional hot water baseboard or radiators, or a normally sized hydro-air system, then your boiler is going to have to operate at 180 degrees in order to effectively heat your home. At those high temps, a mod/con is only operating at about 85% efficiency so you may as well save some money and put in a mid-efficiency boiler that is meant to run at higher temps and will deliver the same efficiency.

This is vital to get the extra efficiency that you will pay so much more for. Don't count on online sellers to mention it.

Siegenthaler reminds his readers about it over and over.

+ 1

 

[in hot water]

A properly installed mod con will save energy cost on high temperature systems also. Most all of them have an outdoor reset function built into the control. There will be plenty of days where you can meet the heat load with less than 180F so it will in fact condense and offer higher efficiencies. Plus most have DHW priority that allows them to boost up to recover the DHW while keeping the heat zones locked out.

The are more complicated to maintain and repair, no doubt. That can chew into the savings if you have to pay someone for the service.

I like the Triangle Tube Prestige and Lochinvar Knight. Both now have that DHW option. Triangle does it with a small tank on board to store and eliminate hot slugs. Expect around 3 gpm DHW when you use it as an on-demand system. It depends on your incoming water temperature. Your milage may vary.

I put a Baxi in my mother in laws, it supplies radiant and generates DHW with a small onboard plate HX and suits her just fine. Endless DHW at one faucet up to around 3 gpm.

They work nicely with solar pre-heat also, no standby loss and in the summer the solar heated water flows right through the DHW hx for instant water heated by the sun.

hr

 

[heaterman]

What Dave BP regarding condensers on high temp systems is true to a point. The thing to remember is that the AFUE rating on all boilers is derived from the following standard. Maximum flow the boiler will maintain at listed firing rate while seeing water temps of 120* on the return and 140* on the supply.
That bares about as much resemblance to real world conditions as I do to Brittney Spears. None.

A standard boiler will very very seldom hit the efficiency it's rated at, while a condenser using variable burner input and water temps will start at 85% and go up from there. If you pipe and pump a condenser right and your system is set up for it you can easily get them to condense yet while supplying 160 or even 170* water. Done it more than once.

I like Viessmann best. (must be my long ago German ancestry) By far the most robust heat exchanger of any out there in terms of design and gauge of metal. The new Vitodens 100 series is right in the ballpark with anything else in a basic condenser and is designed to function as a replacement for a cast iron type. If you want the unquestioned best go with the 200 series. The burner technology is fundamentally different than anything else on the market. It uses flame signal to vary both air flow and gas flow into the burner. Adjusts for atmospheric pressure, relative humidity, monitors CO2 constantly and compensates for different calorific content of the fuel being burned. (No orifice change need to go from natural gas to LP.

Lochinvar has a new wall hung Knight that is a huge improvement over the previous model with the Giannoni heat exchanger. I like their integrated control package also.
Triangle Tube is also a good choice and we've had few problems with the ones we have installed.

 

[Como]

We are putting in a Triangle Tube for sort of similar reasons. It should provide by itself enough to heat the building using radiators and 140F water temp.

We have a separate tank with a heat exchanger for hot water supply.

As it is not operational yet I can not tell you how it works.

 

[djblech]

Thanks for all the info. And I thought this would be an easy decision. I have about a 20 yr old Weil/Mclain 105 btu boiler now. I thick it is about 70%-80% efficient. I am mostly heating with baseboard except the 2 zones I switched to CI radiators. I would like to rip all the baseboard out and install old CI radiators, but my wife isn't sold yet. Just thought with the $ of propane at almost 3$/gal a new boiler might help.
Doug

 

[Ncountry]

I am helping a friend build a home .We are researching an oil fired cond boiler . If it could be vented with pvc the price difference would be at least partially offset with savings from not having to install a 30'+ chimney.Any thoughts?

 

[Como]

I believe it gets a bit tricky with oil as it is not a clean fuel, more contaminants.

Viesmann does one.

 

[Ncountry]

I believe it gets a bit tricky with oil as it is not a clean fuel, more contaminants.

Viesmann does one.

That is where we are at so far. We liked the idea of spending a few thousand$ more on a boiler , rather than a few thousand$ on a chimney. BTW beautiful area you are at .Traveled through there when I was younger. A little farther north we skied berthoud pass before they closed it again.

 

[heaterman]

Call me conservative but I for one am not sold on the idea of a condensing oil boiler. The main reason is that compared to a good multiple pass design you can only pick up another 3-4% in actual efficiency. The reason for this is the calorific value of the fuel itself. A condensing natural gas, or to a lesser extent, LP gas boiler can pick up nearly 10% efficiency through the harnessing of the energy "lost" in the flue gas. This is because of the amount of moisture available in the flue gas. It is much higher than oil.
A good multi pass oil boiler can be tuned to deliver consistent efficiencies in the 87-89% range without condensing. That leaves a much smaller gain to be had if you manage to get it to condense on a normal basis. When you get efficiency up to the high 80% range you can only pick up another 3-4% unless you have a very low temp system using supply water temps of 130* or less. Radiant floor only in other words. (Here is where the issue DaveBP brought up makes itself known) It's just not worth the added expense, complexity and maintenance to pick up only 3-4%.

With the higher flue gas moisture content offered by Natural and LP gas, it becomes a little better investment to go with a condensing appliance. Not so much with oil.

IMHO the absolute best oil fired boiler out there for efficiency, ability to handle low water temps and all around bullet proofness (is that a word?) is the Viessmann Vitola. I have several of these installed from under 100K btu up to 300K and they rock. They are the M1-Abrams tank of the boiler world. Given any kind of care, it is a boiler you will pass down to the next generation of your family. It has the added benefit of being able to change the burner and switch to gas if the opportunity or need ever arose. (but break out the check book)

Using the Vitola 200 mentioned above look at page 4 of the pdf. link here

http://www.viessmann-us.com/etc/med...ed.Par.37611.File.File.tmp/Vitola_200_TDM.pdf

You'll see that the identical boiler cranks out about 83-84% with natural, a point or so higher with LP and about 4 points higher with oil. This is because less of the energy is lost as water vapor with oil than gas. The phenomena holds true with any boiler not just Viessmann because it's a fuel related thing.

 

[pybyr]

Thanks for all the info. And I thought this would be an easy decision. I have about a 20 yr old Weil/Mclain 105 btu boiler now. I thick it is about 70%-80% efficient. I am mostly heating with baseboard except the 2 zones I switched to CI radiators. I would like to rip all the baseboard out and install old CI radiators, but my wife isn't sold yet. Just thought with the $ of propane at almost 3$/gal a new boiler might help.
Doug

If your existing boiler is solid, and you're only looking at a fairly small incremental efficiency increase, it'll take an awfully long time to get a return on the investment. Definitely consider the maintenance/ repair factor, too: a friend of mine who is retired built a small "last" home with a Munchkin high-efficiency propane boiler. A very short time after it went off warranty, it quit putting out heat and began spewing error codes. He opened it up and discovered that the plastic housing on the centrifugal draft blower had cracked. The housing alone was not available as a part-- only some much larger assembly for which the part-only price was north of $400. Being handy and frugal, he used some adhesive to kludge it back together, and it continues to work, and he continues to keep an eye on it. Dread to think what that'd cost a 'regular owner' who had no choice but to have a service technician install the $400+ part. I'm not suggesting that's going to happen often, but it's an illustration of the downside of complex devices with make and model unique internal workings.

If you have places you can insulate or air-seal your house, that's far more likely to pay you back and do so quickly-- and it will make you more comfortable as well.

 

[heaterman]

Thanks for all the info. And I thought this would be an easy decision. I have about a 20 yr old Weil/Mclain 105 btu boiler now. I thick it is about 70%-80% efficient. I am mostly heating with baseboard except the 2 zones I switched to CI radiators. I would like to rip all the baseboard out and install old CI radiators, but my wife isn't sold yet. Just thought with the $ of propane at almost 3$/gal a new boiler might help.
Doug

If your existing boiler is solid, and you're only looking at a fairly small incremental efficiency increase, it'll take an awfully long time to get a return on the investment. Definitely consider the maintenance/ repair factor, too: a friend of mine who is retired built a small "last" home with a Munchkin high-efficiency propane boiler. A very short time after it went off warranty, it quit putting out heat and began spewing error codes. He opened it up and discovered that the plastic housing on the centrifugal draft blower had cracked. The housing alone was not available as a part-- only some much larger assembly for which the part-only price was north of $400. Being handy and frugal, he used some adhesive to kludge it back together, and it continues to work, and he continues to keep an eye on it. Dread to think what that'd cost a 'regular owner' who had no choice but to have a service technician install the $400+ part. I'm not suggesting that's going to happen often, but it's an illustration of the downside of complex devices with make and model unique internal workings.

If you have places you can insulate or air-seal your house, that's far more likely to pay you back and do so quickly-- and it will make you more comfortable as well.

Munchkin had a bunch of issues with their first two-three years production. Fan failure was only one of them. Not my favorite thing to see when walking into a boiler room on a service call. I only installed about 6 of them and said that's enough for me..............Lot's of service calls, lots of weird stuff like poor flue connection right off the back of the heat exchanger inside the cabinet. They are inexpensive as M/C boilers go and good for about 8-10 years of avg life as are most with the Giannoni heat exchanger. Good product to avoid IMHO.

 

[Ncountry]

Are there any non cond oil boilers that can be direct vented?

 

[huffdawg]

Heaterman, are you familiar with the Buderus GB 142. Im trying to find out some operating sequence parameters. I will be sending heated water through it via a primary loop and eko. I will be installing closely spaced tees between the GB boiler circ pump and the gb Boiler. I tried to get this info from the contractor who built my system ,but he wont answer my emails . He either doesnt know or hes not interested after he got his 12G. I also tried contacting buderus boiler and they're not interested in talking shop with an unqualified person.

 

[heaterman]

Heaterman, are you familiar with the Buderus GB 142. Im trying to find out some operating sequence parameters. I will be sending heated water through it via a primary loop and eko. I will be installing closely spaced tees between the GB boiler circ pump and the gb Boiler. I tried to get this info from the contractor who built my system ,but he wont answer my emails . He either doesnt know or hes not interested after he got his 12G. I also tried contacting buderus boiler and they're not interested in talking shop with an unqualified person.

I gave no experience with the GB personally. I know a lot of guys out east that use them but I'm waiting a while until I see how that aluminum heat exchanger holds up.

I'm assuming your plan is to pull the system return off, send it through the EKO and then dump it back preheated before it gets to the GB.

Piping wise I don't see how that would mess things up for the GB. Keep the centerline of your tee's no more than 4 pipe diameters apart and it should not affect flow. To quote the immortal words of Gil Carlson who was B&G's head engineer for years...."What goes into a tee, has to come out of a tee". I do think you are going to want to match the flow rate of the GB side and the EKO side pretty closely.
My main concern would be the water and water treatment in the system because you are mating up two boilers made with very different material. I know at the very least you will need to make sure the antifreeze you have in the system is compatible with both iron and aluminum.
I don't think the BC10 control will know the difference where the heat is coming from when there is a call for heat. Neither would I think the control is sophisticated enough to figure out that even though the burner hasn't fired it's still hot enough........so something is weird.

Seriously. Check out the antifreeze/multi metal inhibitor package your installer put in. That may be the fly in your ointment.

 

[huffdawg]

I'm assuming your plan is to pull the system return off, send it through the EKO and then dump it back preheated before it gets to the GB. Yes thats right

[/quote]Seriously. Check out the antifreeze/multi metal inhibitor package your installer put in. That may be the fly in your ointment.[/quote]I dont use any glycols or inhibitors ,contractors instructions.

 

[GT26]

For new construction what do you guys think of the Versa-Hydro- Solar, http://www.htproducts.com/versa-hydro-solar.html
with solar storage and maybe later, wood gassifyer.
I'm thinking along lines of OP that resale value might be better.

 

[heaterman]

I'm assuming your plan is to pull the system return off, send it through the EKO and then dump it back preheated before it gets to the GB. Yes thats right

Seriously. Check out the antifreeze/multi metal inhibitor package your installer put in. That may be the fly in your ointment.[/quote]I dont use any glycols or inhibitors ,contractors instructions.[/quote]


You are correct on the inhibitor package and other chemicals. Buderus says not to use them. What I was referring to, assuming you had antifreeze in the system, was to make sure it's an all metal type of glycol.
That being said, there are some manufacturers using aluminum block boilers that go the other way and say that if you don't treat the water with their particular "methyl ethyl good stuff" your warranty is void. Weil McClain comes to mind....... Also be aware that your GB should not be filled with water that has gone though a water softener.

Re; your original question, I don't see anything that would get screwed up by piping your wood boiler into the system as described. But I would surely defer to Buderus or your installer on this.