Cast iron or condensing??

ryangtogtx

I am going to be needing a new boiler soon.  I had a pump go out and when it was replaced, the tech said to start saving money for a new boiler.  My question deals with which way to go upon replacement.  I havecopper fin baseboard radiators.  The tech wasn't sold on the high efficiency boilers and thought I should just replace with a new cast iron unit.  He said with radiant baseboards I wouldn't be maximizing the efficiency of a condensing boiler.  He thought I'd probably get around 89% as opposed to 82-85% out of a cast iron.  I think he was implying the extra cost for a condensing unit wouldn't pay off or would take a long time.  Any thoughts on this?  Also, he said with the condensing units, you need to have a yearly cleaning on the heat exchanger which eats into your cost savings.  Is this true with units that use stainless steel or just aluminum?  Thanks for any help.

CMadatMe

Wrong Approach

The tech is that a tech. The first words out of his mouth should have been. You really need to start with a heat loss. Let's make an appointment for one of our salespersons/heating specialist to come out and speak with you.



No person can specifically anwser your question concerning the mod/con without doing a heat loss and comparison of heat emitters to that loss. There are plenty of ways for you to get the maximum efficiency from a mod/con with fin-tube board. You may find from that heat loss that your existing baseboard is oversized. If that is the case, you can run a lower water temp at design. You could run a 30 degree delta-t vs a 20 degree delta-t. You could slowly change out the exisiting board to a high capacity baseboard. There are numerous ways to approach this and you should start with finding a contractor whose specialty is in low temperature hydronics.



As far as service, why wouldn't you want to service a piece of equipment that you paid top dollar for? Do you not change the oil in your car every 3,000 miles. Preventive maintenace on any thing you own saves you not only money  but inconvience.



PS, I have a customer that installed a mod/con on fin-tube board. We did the heat loss, changed a couple of the zones board to hi-cap and used a grundfoss alpha as a system pump. His boiler has never seen more than 135 degree water.  The house is 70 and comfortable in all 5 zones. He replaced a Buderus GB mod/con with a Viessmann Vitodens 200. Savings this year over last to this point 33%. Thats changing  from a mod/con to a mod/con. We are in NY and it's been a darn cold winter.

NRT_Rob

I'm not sure

that a low temp specialist will give an unbiased opinion.



however, that said, a mod/con will run most efficiently on any system and even if you need 160 at design at a regular 20 dt, most of the time you'll be running in condensing mode, as in more than 90% of the time most likely and I don't think I've ever seen an installed baseboard system that actually needed 160 at design: the vast majority are oversized because no one did the math.



I would choose a unit with less maintenance requirements. the service calls can eat up some change for sure, and some boilers don't need as much TLC as others.

Charlie from wmass

Some cast iron is 86 afue

or even a point or two better. but what is your fuel source.

ryangtogtx

Natural gas

Fuel type is natural gas.  I think he was suggesting a cast iron for my application because the cost savings would take a long time to gain back.  He said a cast iron running with an outoor reset can get a good efficiency and cost about half as much and also not need a yearly service call.  He said if my only reason for a high efficiency was to save fuel then he'd definitely put one in, but if I was doing it to try to save money, then there are other options that can work well and not cost an arm and a leg.  What are some good cast iron units to consider?  Thanks for the input so far.

CMadatMe

Is Saving Fuel

Not saving money?  Did the tech explain the federal tax credit or any local utlity rebates? I think he was streching it saying that the price is double. Once you start adding outdoor reset controls to a Burnham ES2 (which is the only 87% atmospheric cast iron gas boiler to date) you are pretty close to the mod/con and don't forget to add the cost of the required chimmney liner. After the tax credit alone a mod/con ends up costing less. Now add in any local utility rebates.



The ES2 is a very nice boiler. I feel Burnham is a step ahead of the other American boiler manufactures and they did a great job in design and thought with this piece of equipment. The cost difference between it and a mod/con is very minimal.

CMadatMe

Unbiased

I didn't know a heat loss could be bias or that heat emiitter output at given temps and flow rates could be bias. Learned something new today.

NRT_Rob

right

way to miss the point.



the point was, he was asking if he SHOULD get a mod/con.



a low temp specialist would of course tell him yes.



the question is, would the specialist be right?



I'd say sure, usually, but then, I too am a "low temp specialist". thing is, being a low temp specialist doesn't make the case for low temp.

CMadatMe

I agree

It doesn't make the case but a customer would sure have a better shot at getting all the correct information and education to make the best decision concerning what system fits them the best. I just don't understand how someone (in this case the tech) could state that a particular product is not best or another product may be better without doing all the necessary homework to make such a statement.



I probably should have not  used the term "low temp specialist" and should have used "heating specialist".  I'm sure a person of your caliber would have done a heat loss and looked at emitter output before making any statement.

Supply House Rick

Radiantwizard

"He replaced a Buderus GB mod/con with a Viessmann Vitodens 200. Savings this year over last to this point 33%. Thats changing  from a mod/con to a mod/con."

How? That's amazing! weren't the both running in the 90%+ range? That's a significant savings, what's their secret? Thanks

CMadatMe

Supply House Rick

I don't believe all that savings came from just the boiler. When we approached this we took at look at the whole system. After heat loss calculations we decided to change a couple of the zones from residential base-board to hi capacity to allow for a deeper curve. We used a Vitotrol 300 remote control for indoor-feedback back to the boiler so the control would take both the outdoor temp and what was going on indoors into consideration. We scrapped the existing primary/secondary piping for a low loss header with temperature sensor. This eliminated the temp drops when multiple zones called so it allowed us to dial in without having to worry about water temp fluctuation. The temperature sensor also sends feedback back to the boiler providing supply water temp into the heating curve calculation.  I do feel the addition of the Grundfos Alpha as a system side pump has also helped. As those zones open and close that pump keeps our flow rates where we want them so we are not screaming through the smaller zones and we stay consistent. We are also running a 30 degree delta-t.

Mark Eatherton

Curious...

How are you forcing a 30 degree F delta t on the system?



I understand the design principles behind it, just as I understand the design principles behind a 20 degree d.t, but I have only actually seen a 20 degree d.t. once.



Have you actual witnessed a long term 30 degree d.t. at conditions other than design conditions?



To my knowledge, the only way to extract a 30 degree d.t. is to increase load, or decrease flow, and decreasing flow is not beneficial to delivering heat across an emitter.



Just curious.



ME

Supply House Rick

So really the boiler change out was unneccessary

You utilized controls and a re-engineering to save the 30% correct? Why was the GB142 removed?

"He replaced a Buderus GB mod/con with a Viessmann Vitodens 200. Savings this year over last to this point 33%. Thats changing  from a mod/con to a mod/con."

CMadatMe

Change

He was a Buderus user true and blue for years and put in alot of these boilers. He was growing tired of the call backs for warranty issues and wanted to look at another boiler line. When the new Vitodens came out and the price dropped he decided to take a look at the boiler. So we took care of him on the Vitodens and put it in his house. From his feedback he feels that the control is miles ahead of the GB and allows him to better tune in his homes need and his comfort. So in turn he feels he can deliver better comfort systems to his customers with the Vitodens over the GB. I tend to agree with him but this is just one application and a couple of persons observation. He did have a Buderus RTU providing indoor feedback but it just didn't do the job he wanted. 

Supply House Rick

He was growing tired of the call backs for warranty issues

Was Buderus aware of the ongoing problems they were having with their equipment? They couldn't correct the problem? Just curious, what will the viessmann control do that the GB142 wouldn't? I also believe that the Vitodens had a recall for being a Fire Hazard. That seems pretty serious...

NRT_Rob

you're trying pretty hard here rick

are you seriously going to pretend that the GB142 hasn't had more issues than the vitodens?



we could turn this thread into an expose on such issues if you like. I know a lot of people like the GB but it is not the most problem free boiler I've seen out there.

Supply House Rick

Rob

Just checking on the GB142, I have sold over 100 of them and except for a few antifreeze issues and lack of yearly maintenance they are purring like kittens. I guess I never drank the Orange Kool-Aid.

CMadatMe

Mark

Just logged on and saw your post. I'm hosting a class this evening and will post you a reply tomorrow. Thanks

Chris

EricAune

GB problems.....noooo.....

Gas valve, RC10 control, dried-out & cracked condensate traps, more flame sensors than could be imagined, oh and lets not forget ITS ALUMINUM!



I guess you could say there have been some problems