What do I need to consider changing to a modulating high efficiency boiler

Reply

  #1  
Old 11-21-07, 11:28 AM
E
Member
Thread Starter
Join Date: Oct 2007
Posts: 15
Received 0 Votes on 0 Posts
What do I need to consider changing to a modulating high efficiency boiler

I am replacing a 90k btu oil boiler which supplies single zone heat to a 1950s single level house. I don't care to get frilly and add zones or tie into my domestic hot water. Boiler out, LP boiler in. The oil boiler was very adequate (although not very efficient) will a modulating 45 - 100 k lp boiler be sufficient and will replacing the old circulating pump with one of similar size do the ticket with a new boiler? Please don't tell me to call a contractor because I have and the best I can figure is they want to charge me $3600 labor for a two day job. The bid was close to $7000 to pull, replumb, vent and wire. I offered $1500, 2 guys 2 days and adjust if they ran into something unforeseen, and you would have thought I kicked them in the water bag. I just want to make sure I have considered everything before I buy a new suitcase stainless steel high eff. unit
 
Sponsored Links
  #2  
Old 11-21-07, 01:11 PM
X
Member
Join Date: Nov 2005
Location: USA
Posts: 2,459
Received 0 Votes on 0 Posts
Tempting though it is to get into a discussion of what it costs a contractor to do business these days, or the usefulness of getting 3-4 bids, I won't go there right now.

Considerations:

1) spend the time (all of a couple hours) and do a decent heat loss calculation for the house. Maybe you don't need 45-100k but something much smaller, particularly if you are not going "frilly" or using an indirect water heater. If you live in the NE US, your heat loss on a design day is probably under 60k, and maybe under 40k for a typical single-floor 1950s house. Why do 45-100 if you only need 10-50?

2) remember that most insulating and air-sealing projects save you way more money on energy costs than a new boiler. Even one that you buy from a friend of a friend of the guy at the local supply house who can get you a deal on a scratch 'n dent and install yourself.

3) for a mod-con, I agree that stainless steel is the way to go. I would consider the Lochinvar Knight, Triangle Tube Prestige, Viessman, and Munchkin. Viessman if you want to drop some serious coin, Munchkin if you want to go inexpensive. Some of these are probably better behaved than others with propane.

4) The ability to understand and follow the manufacturer's directions for water piping. Some of these boilers allow you to run direct. Some require primary/secondary piping. Some of these heat exchangers have very high head losses, hence the need to pump high volumes through the boiler, much higher than you would through the distribution circuit(s). So you pipe primary/secondary.

5) The ability to understand and follow the manufacturer's directions for intake and exhaust piping. If they say use stainless, don't use galvi. If they say use CPVC, don't use PVC. If they say keep the total equivalent length of the exhaust under 50', don't make it 60'.

6) The ability to tune and evaluate the burner and controls to achieve the proper combustion specs, etc. It is my understanding that propane is less forgiving than gas in this regard, but more forgiving than oil. Normally, this requires some fairly sophisticated testing equipment, and the training in how to use it. This is particularly true with the new mod/con boilers.

7) The ability to understand and follow the directions for condensate disposal. Condensate has a pH of about 3-4. It's an acid. It will quickly eat through cast iron. What is the waste/septic piping in your 1950s house made of? It will eat concrete, given the right conditions and enough time. It may be illegal in your area to drain untreated condensate into a municipal sewer. Treating it is simple and options abound, just get it right.

8) The need to consider the following scenario: you have a problem -- say the boiler fails while you're away, house freezes, pipes burst and you've got $25k in water damage. Your insurance company gets involved. They will immediately ask for the name of the contractor and start running down the permit paper trail. If you have been following any of the news lately about homeowners insurance, you clearly understand that they are on the lookout to deny any claim resulting from violations of the conditions of your policy, and will drop you like a hot potato on the first incident. Evaluate the risks and benefits of this project and act accordingly. We do it it all the time with DIY projects, whether we think about it or not. Personally, I draw the line at projects that simultaneously involve combustion, water, and electricity.
 
  #3  
Old 11-21-07, 02:47 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 3 Votes on 2 Posts
Everything that Xiph said, and:

I am 100% confident that I could install a new boiler system in my own home. I believe I have the skills, knowledge, and tools to do so.

Based solely on Xiph's point #8 I would not do the job myself. I would bite the bullet and hire contractors, UNLESS the job was properly permitted and inspected by local building department, AND I notified my insurance company before starting work of my intentions, and had an OFFICIAL ruling from them that I would be covered after the fact.

Some localities won't even PERMIT a homeowner to install a heating system unless he is a licensed professional.

Xiph's example of $25K water damage... OK, could be even WORSE than that... what if you had a fire ? what about loss of life even ? Sure these risks exist even if a pro did the job, but at least you would be afforded some protection by your insurance company, and bad things wouldn't sit on your own conscience for the rest of your life...

This really isn't a trivial matter... ignore it if you wish, but don't be complaining that people here at diy.com aren't holding their end of the bargain. They are doing what is BEST for the people that come here for help, even if that means giving them some 'tough love' and telling them to call a contractor.

By the way, Xiph mentioned a heat loss calculation... and so did I back on 10-10-07 when you first posted... did you do it ? It's good advice, and will save you serious bucks in the long run.
 
  #4  
Old 11-21-07, 03:10 PM
H
Member
Join Date: Nov 2007
Location: St. Louis
Posts: 17
Received 0 Votes on 0 Posts
my 2 cents

I'm a total DIY guy in the middle of this same deal.

I'm replacing a 40 year old gravity feed dinosaur with a Viessmann unit. Making a lot of mods along the way and lucky enough to have a contractor to develop a plan and guide me through this. I'll do all the dirty work and he'll do the final inspection and test/adjust. This is the only project I've called in for outside help and it's part of a total gut rehab - I wouldn't have it any other way.

The contractor's costs you mention - remember it's a lot more than labor you're paying for included in that. It's the cost of doing business - tools, training, insurance, etc.
 
  #5  
Old 11-21-07, 05:16 PM
E
Member
Thread Starter
Join Date: Oct 2007
Posts: 15
Received 0 Votes on 0 Posts
Thanks for the advice

Wow - hearing from you guys makes me wonder how we will be able to change a light bulb in a few short years without the help of certified contractor. All I asked for was pump characteristics, not a lecture on gas, water or electric - bye the way that pretty much does limit one to light bulb swaps. I'm sorry if I sound a little smart and I'm sure you all are in CYA mode but I didn't sign on for lectures just info. I have done quite a bit of research on modulating units and the ones I'm interested in start at between 80 and 100k (max with modulation as low as mid 30s in some) and step up and even if a heat calc tells me less Oh Well.
I own my own business and I am well aware of the costs to run a business and I am also aware of when I'm getting porked. I really don't have the time to mess with this but I'm not going to pay $250/hr for Harry Houdini let alone an HVAC guy. So from the response I've received from you none of you have any clue as to what I'm asking because you wouldn't do this job without fear of putting the eastern seaboard in harms way. Please let people respond who actually know the answers to the question I'm asking THANKS
 
  #6  
Old 11-21-07, 05:33 PM
Join Date: Aug 2006
Location: usa
Posts: 902
Received 0 Votes on 0 Posts
No one here knows what your abilities are, or what you are capable of doing. If you've been on this site you'd be rather amazed of some of the dangerous and illegal things folks have done or are planning to do. It is only prudent to offer some general advice on the safety and legalities of doing such a major and potential dangerous undertaking. No one on this site is getting paid to offer free advice or guidance. Also remember that whatever is written here is archived for others to read and follow in the future.

Xiphias gave you the best advice when he told you to do a heat loss before doing anything.

That being said I am one of the homeowners on here who did put in his own boiler system, after learning as much as I could, getting the proper permits, and having the system inspected, and then tuned by a professional.

Pete
 
  #7  
Old 11-21-07, 05:34 PM
Who's Avatar
Who
Who is offline
Member
Join Date: Jan 2006
Location: San Jose
Posts: 2,175
Received 0 Votes on 0 Posts
You asked if you were considering everything. They took their time to try to help you and you responded with sarcasm.

Go to "heatinghelp" and ask... they'll know better than us lightbulb changers.
 
  #8  
Old 11-21-07, 05:49 PM
X
Member
Join Date: Nov 2005
Location: USA
Posts: 2,459
Received 0 Votes on 0 Posts
The great thing about the advice here is that it is free. Free to ask, free to give. Just as you are free to leave if you don't like it.

We could probably be more helpful if you a) lost the attitude, and b) described which brand/model of boiler you are considering, more about how your house is piped, what kind of radiation you have, and what your "old circulating pump" is. Is it a B&G from the 1950s? A Taco from the 80s? What model? Please try to remember that we are not standing in your basement looking at who knows what kind of existing piping, venting, circulator, etc. If your boiler setup is at all like some of the ones people post here (all these photobucket links), asking whether you can use the old pump or not is pretty foolish. Provide better information.

You asked about pumping. I believe I addressed that (see #4 above) given the limited information you provided. Some boilers require primary/secondary. Some don't. You didn't say what boiler, so we can't look at the I&O manual to see what they say.

You wanna install your own boiler, go for it. You got a question, most likely we'll answer it. Fire away.
 
  #9  
Old 11-21-07, 06:26 PM
E
Member
Thread Starter
Join Date: Oct 2007
Posts: 15
Received 0 Votes on 0 Posts
Apology

I just felt I was being lectured - didn't set well 30 years ago- guess it still doesn't. I will get it done and I may ask some more questions. I will have it inspected and I will contact my insurance man - good point -. In reading through past I was put off bye help provided car king llc.
Please tell me why trinity units have gotten a bad rap - they appear to be on the leading edge from the outside looking in, great web, great manuals, great tech pages. I've seen the recall of 4800 units based on the failure of one and that sounds like (based on installation manual) a bad install (probably some guy who thought knew what he was doing), Is there any thing else to know if I am considering one of these units.
 
  #10  
Old 11-21-07, 06:32 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 3 Votes on 2 Posts
Originally Posted by eaglepines View Post
Please let people respond who actually know the answers to the question I'm asking THANKS
In your entire first post, you asked ONE question. You got the best answer you could get based on what we know about you and your existing system.

You said, "...I just want to make sure I have considered everything..."

And in response you got quite a list of things to consider. Maybe this isn't what you wanted to hear ?

What _do_ you want to hear ? That it's perfectly OK for a novice to undertake a serious project that could possibly result in property damage, injury, or even death if mistakes were made ?

Of course we're in CYA mode, who wouldn't be in such a litigious society ? But the sad truth is that we're also trying to C _YOUR_ A !

Anyone who wants to respond is free to do so, nobody is stopping them, and by the way, we DO know the answers to the question you are asking, and we gave you those answers. Like it or not.
 

Last edited by NJT; 11-21-07 at 06:49 PM. Reason: crossed in the mail, apology accepted.
  #11  
Old 11-21-07, 07:04 PM
E
Member
Thread Starter
Join Date: Oct 2007
Posts: 15
Received 0 Votes on 0 Posts
Apology

I just felt I was being lectured - didn't set well 30 years ago- guess it still doesn't. I will get it done and I may ask some more questions. I will have it inspected and I will contact my insurance man - good point -. In reading through past I was put off bye help provided car king llc.
Please tell me why trinity units have gotten a bad rap - they appear to be on the leading edge from the outside looking in, great web, great manuals, great tech pages. I've seen the recall of 4800 units based on the failure of one and that sounds like (based on installation manual) a bad install (probably some guy who thought knew what he was doing), Is there any thing else to know if I am considering one of these units.
 
  #12  
Old 11-21-07, 07:08 PM
X
Member
Join Date: Nov 2005
Location: USA
Posts: 2,459
Received 0 Votes on 0 Posts
No prob, dude.

I don't follow the mod/con market much. Not sure if NTI Trinity are getting a bad rap or not; all I know about them I read on the internet....

But what I've read:

- occasional difficulty getting parts
- high head through heat exchanger requires a big pump and thus probably almost always primary/secondary piping. That said, I believe the hx design is similar to or the same as a couple other stainless mod/cons, so it's not a uniquely NTI issue. Nor is primary/secondary a bad thing. It just requires a bit more planning and attention to detail.
- venting options are a little more rigid
- the controller is not the Honeywell MCBA, which appears to be leading the pack as a "standard" among other modcons

Even though mod/cons have been around for a while, I think they still have a ways to go before we really understand how much it will take to maintain one for a decade or so, and where the flaws are that result in premature failure, recalls, etc. This is definitely NOT your father's 50-year block of cast iron. It's a high-tech, computerized, finely tuned sensitive instrument. It should last longer than a laptop, but not as long as my 1970 Montego.
 
  #13  
Old 11-21-07, 08:20 PM
E
Member
Thread Starter
Join Date: Oct 2007
Posts: 15
Received 0 Votes on 0 Posts
Thanks

Get your point - family has 55 t bird and all it needs is a little turtle wax and a quart of oil.
I will attempt to contact someone at NTI to see if this unit is a fit for my system.
 
  #14  
Old 11-21-07, 08:37 PM
Who's Avatar
Who
Who is offline
Member
Join Date: Jan 2006
Location: San Jose
Posts: 2,175
Received 0 Votes on 0 Posts
Eaglepines, go to slantfin dot com and get a copy of heatloss explorer. Without a heatloss calculation, how will you know if the system was sized properly?

The smallest NTI is a 15-100 unit... gives a nice modulation range but in order for it to work with the pressure switch (probably a better solution than a low water cutoff - less maintenance) it requires the same boiler loop circ as the Ti150 and that's a Grundfos UP26-64 or Taco 009. Those pumps are bigger, costlier and consume a fair chunk of electrical compared to others.

On a budget, I'd look at Munchkin's offerings. They have a 50 MBH model that may very well better fit your heatloss requirements.

My favorite is the Triangle-Tube Prestige. Simple downfiring self-cleaning design that is low head (has a small internal 3 speed pump that could be piped direct in your case). It's costlier than the Munchkin or the Trinity (which are made in the US and Canada respectively with a HX sourced from Europe). The Prestige is made in Belgium and not pieced together here so the QC tends to be much better. The downside of the Prestige is that it only modulates down into the 30 MBH range, which is fairly high for smaller homes - I'm in that boat but knowingly accepted that limitation. Between a 2 gallon high volume heat exchanger and the MCBA control parameters it doesn't short cycle.

Anyway, first things would be to do a heatloss calculation. Why don't you do that first? You'll need to know your design temperature - coldest expected day of the year, and more or less what insulation, windows etc. It'll do the heatloss room by room and give you a total. The total is pretty conservative. Based on that maybe we can steer you towards options with that size in mind.

It's also an excellent idea to keep an indirect water heater in mind. You don't have to install one but you should at least make sure the piping is in place for one. With a modcon there is no more economical way to heat your water short of solar - it also gives your boiler something to do over the summer.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: