TT mod con or Buderus Cast iron with outdoor reset

binskibok

2000 sf cape in Farmington Ct needs boiler replacement  just ran natural gas to house  current situation 50 year old oil fired boiler  hot water thru coil 1st floor has black pipe with convectors and 2nd floor has copper baseboard. heat loss calc 81k    new setup will have 3 zones (1sr floor , 2nd floor and basement) with a 40 gal TT smart 40 indirect for DHW What system is a better fit for a boiler replacement. The initial savings will be significan with either a TT solo 110 mod con or a Burnham RV4 or Buderus GA124/23 cast iron with outdoor reset.  I'm not sure the mod con fits the application because of piping config. The average oil consumption over the  last 3 years is 950 gallons . Should I go for the mod con and it's AFUE of 92% or should I opt for the bullet proof cast iron at an 88%.? Your thoughts would be greatly appreciated    

CMadatMe

I have a question

Is this your house or the customers house? I ask because I would think that you would want to leave it up to them whether they would like to take advantage of the Federal Tax Credit and the local utility rebates if they are offered in your area. Not to sound like a jerk but shouldn't the choice of boiler be there choice based on all the information you as the contractor are providing them. If I were the homeowner I would think that you would be doing me as your customer a dis-service by not letting me know about the tax/utlity rebates and credits and allow me to make the decision that fits my needs. The cost of a mod/con of 98% afue after the rebate and tax credit will be just as much and in some cases less than the cost of the 88% or 92% afue boiler you may choose. Just because you may not want to pipe a certain way shouldn't influence the needs of your customer. Leave the decision up to them. Let them decide based the information you provide them as the professional.

Again, do not want to come over as bashing you just giving my 2 cents.

binskibok

Still undecided

Thanks for getting back to me. I do own the house and  plan to live here for the remainder. Since any  heating system is a critical portion of costs associated with living in New England I just want to do  the necessary research before commiting to a boiler and contractor. I am familiar with the tax credits currently available but I have doubts about the mod con in my particular situation. I mentioned the piping config so I'm doubtful I'm be condensing at all. I'm also wondering about the costs associated with the annual maintenaince.  I do have a small cape so that's  why I mentioned the AFUE  ratings The initial saving realized from the upgrade will be significant but the 5% difference  between the boilers is minimal.  I looking for years of trouble free reliabliliy. Any component that goes wrong with the mod con would clearly diminish that small margin. Other factors include water PH balancing,  system flushing of the old system  and gas and water filters both  which not one contractor mentioned during our walkthrus . I'm just trying to plan to get the  best return on investment  and  get the best boiler for my application.   Thanks again for you input    

Jean-David Beyer

I have doubts

I am a homeowner, not a contractor.



I have a small (1150 sq..ft.) Cape Cod in New Jersey. I calculated my heat loss as between 30,000 and 40,000 BTU/hr. I have radiant heat in the slab downstairs. I put in 14 feet of Slant/Fin in each room upstairs. So I will certainly get condensing running the heat downstairs, since I plan to set the temperature of the water on the coldest day to 120F.

Likewise, I have so much Slant/Fin upstairs that it calculates out to 140F water up there on the coldest day. So I expect a lot of condensing. Especially since I have outdoor reset and can run a different reset curve for each zone. I have no experience with this during the winter yet, so I may have to diddle the temperatures and reset curves to get them right.



Your 81K BTU/hr could be correct, since your house is nearly double the size of mine and you are further North, all other things being equal, as I am sure they are not. Did you examine the radiation of your convectors and baseboard? If you have too much capacity there, you might be able to lower the boiler temperature until it is just a trifle too high and get it into condensing range a lot of the time. The combination of condensing and modulating with outdoor reset might make this a practical proposition.



My boiler has an aluminum heat exchanger. I do know how reliable that is going to be. When all is said and done, you may have to guess based on estimated boiler life, and how much condensing and modulating you will be able to achieve.

TonyS

950 gallons of oil

would be about 1330 therms of gas, gas here is about 1.27 a therm, use would be about 1700.00 a year but it will be less with either new boiler, so lets say 1500.00 a year. Your picking up 7 percent which is 105 dollars a year (we didnt add the cost of running primary secondary pumps on the modcon so it even less) Lets say the modcon goes 15 years and the buderus 30. In 15 years the modcon saved you 1500 bucks plus the rebate1500, and thats if you havent already consumed some of your tax credit on insulation, doors,windows ect. So your at 3000.00 savings in 15 years. Now after 15 years you need a new one. Will the new one be less than 3000.00 No its going to be alot more. There really is no reason to use a modcon that I can see. Check out the new Burnham ES2, cast iron, 110 return temps, lifetime warranty,outdoor reset. American made.

TonyS

Navien water heater

As far as the water heater goes, a tankless navien is 98% eff. It is the most efficient water heater made and cost about the same as a indirect, 15 year warranty, will get you the tax credit, no standby loss.

CMadatMe

A new take based on your reply

First let me start with Tony's recommendation. Tony, by the time you line the chimmney for the ES2 and add the out-door reset card you spent more money then the mod/con. For the homeowner.

I totally understand your thought process. While I'm in NY I'm  also originally from New England and understand what you are talking about. Let's start fresh and back to basics concerning your project and question.

I understand that you have done the heat loss but I have another question. Have you compared the heat loss of each room to the max out-put of the exisiting heat emiiters in each room? You need to. Here is why.

Let's take a room with baseboard in it. What's the loss of that room? Let's say it's 4,800 btus. That means you would need roughly 8 foot of fin-tube baseboard (Brands of residential baseboard put out between 590 and 600 btus per sqft.) to heat the room with 180 degree water when it is 0 outside.  How many days is it zero? Your only about 100 or less miles from me and I've lived in CT so I'm going to give the benefit of the doubt and give you 7 days.

Now that room has a total of 12 feet of baseboard because back in the day someone decided to wrap the room which is very common. The total btu's I can get out of 12 feet of baseboard with 180 degree water temp is roughly 7,000 btus. But I don't need 7,000 btu's to heat that space ever. So I can lower my water temp to match the btu required by the heat loss to heat the space when it is zero outside.  This is where the mod/con plays a better role then the cast iron boiler. The mod/con is set up to do this. The cast iron boiler is not. You have to start adding controls that are not generally controls from the boiler manufacture but from a third party or you have to order cards to plug into boiler mfgs controls. With the mod/con you are dealing with a complete system that is ready to go, with the cast iron you are not.

If you take a look at the Viessmann Vitodens 100 which is perfect for this application. The boiler offers you the 95% afue you need for the tax credit/rebates,  the outdoor reset you need and the simplicity of not doing primary secondary piping. It also has a much better warranty than the Triangle or any other boiler you listed here. It has a 2 yrs parts (the cast iron guys 1 yr) and limited lifetime on the heat exchanger (just like the cast iron guys).  We do not discuss pricing here but it would be wise to look into this boiler.  Probably comes pretty close to that ES2 boiler once you add the liner, extra card and extra labor to install that liner and the ES2 does not qualify for the tax credit.

Best of Luck

TonyS

Ok lets change the options

We can use a Revolution@88%and go through the wall, then add a tekmar outdoor reset and we already have a more efficient way to make domestic with the Navien which will give us the tax credit. Figure it with a Burnham pvg at 85% it doesnt matter. Use a crown boiler. Throw in another thousand bucks, it just isnt there...there is no payback,it makes no economical sense to buy a modcon now. I owe it to my customers to tell them what will cost them less upfront and in 30 years.The federal government cant keep giving this tax break forever. And the tax break is not refundable and is cumuative with many other things. Truth is without a tax break the modcon doesnt even come close to competing. I think when you see these modcons start failing in a few years it will be easy to get people to change back to cast iron. Its just proven to be a great material to make boilers out of. This is probably why they are willing to pay more for a cast iron boiler in Europe than a modcon.

CMadatMe

You are Way off base but you have a right

to your opinion.

My boiler will qualify for the full 1,500 tax credit..Remember the tax credit is 30% of the job upto the 1,500 bucks...Please give us the actual tax credit on the Navien..won't be the full 1,500 bucks unless your telling us your fudging invoices.

Based on his location the RV will only qualify for a 500.00 rebate from his local utility the mod/con 1,000.00 and if he installed an indirect another 300.00 that's a total of 2,800.00...So your telling me it is in the best interest of the customer to give up $2,300 compared to less money with the system you recommend based on your thought that the mod/con will only last x amount of yrs. 

Ok...We are in 2009....Did you know by the yr 2015 all boilers sold in the US must have some type of out-door compensation? Did you know that beginning next yr Burnham will be implementing the new ES2 control into all their boilers. My point is..No matter what product you purchased there are going to be changes and sooner then we think.

 

TonyS

I guess its just a matter of

doing the math. If the Vito has the same warranty as the cast iron and you really feel its going to last as long, you may be right. What is the warranty exactly on the 100? Maybe I'm wrong but it just seems ridiculous to be burning carbon based fuel for heat when the the ground has all we need. I have a geo thermal w/w and my heating bill is less than the cable bill.I know the new units will have ecm motors and COP,s that will blow us away. I will probably replace it long before its payback period on the boiler it replaced, depends on the price of fuel. I would rather see customers start converting their houses to low temperature radiant heat instead of spending more money on modcons, they are going to get better energy savings and they will be ready to convert to geo when the time comes. If a customer has a 25 year old boiler in decent shape, do you feel his money would be better spent on converting to radiant or spending the money on a modcon? A similar circumstance in my household now, My wife was going to buy a Prius, she drives about 30 miles a day to work and shopping ,whatever. She decided to wait till the chevy volt is available or the Prius has the plug in Lithium. She will then basically not use any gasoline then only on longer trips. I know I know you can always wait, but really this stuff is coming right around the corner. I'm also having a chimney installed in my house for a wood stove because if this whole thing collapses we will still have heat. 

Jean-David Beyer

low temperature radiant heat

"I would rather see customers start converting their houses to low

temperature radiant heat instead of spending more money on modcons,"



I do not know what you mean by low temperature radiant heat? I have ordinary radiant heat (1/2 inch copper tubing in a slab). On coldest days it is set to put 120F water into that slab, and is set to drop that all the way to 75F on warm days with outdoor reset. How much colder can you go?



And with such low temperatures going into the slab, and lower yet coming out, I would expect to get a lot of condensing.



So I expect to benefit from that mod|con boiler. The boiler manufacturer claims to get 93% efficiency with the thing and up to about 98% if the return temperatures are low enough. I do not think I could get 98% unless I did mostly ice melting as it requires 60F return temperature to get it. But at 75F return, I should get about 96%.



I did not calculate just how much money modulating with outdoor reset and condensing, also with outdoor reset, will save me compared with a non mod|con boiler. I think it will be quite a bit. Since I do not know the price and mean-time-to-failure of the heat exchanger, nor do I know the future prices of gas, I cannot tell if it is going to pay off or not. I also do not know how to put a price on lowering the environmental pollution by running more efficiently, but it is surely worth something.

TonyS

That is low temperature radiant heat

The reason I say low temperature JD is because some radiant systems run at 140 and higher. Most Geothermal water to water units will only make 120 degree water. That is why when you have radiant installed you look for the system that will give you what you need at the lowest possible water temp. In slab is usually the lowest, staple up being the highest.  The efficiency of some of the new air to water systems will be very high also. I believe that if you have a high temp hot water system in the future, and the only way to obtain those temps is with fossil fuel, the cost to operate between a future heat pump and a fossil fuel boiler will become so wide that only a very small percentage of people would retain their water systems unless of course they have low temp radiant.

Roland_18

Mod-Con or cast iron

 This is the kind of discourse we sorely need. I applaud all of you for expressing your opinions in a masterful and intelligent manner.

 There is no one size, or system, fits all and it is confusing for a homeowner to choose wisely when faced with the purchase of a comfort system. I only wish I had been more educated when I made that choice, live and learn.