I thought I knew

Canuck_3

Hello Wallies - It's been a while since I've been here but when it came to this quandry I knew that I had to ask here.

We're just getting into replacing a wall hung boiler with a new unit. The owner wants something different than the NTI that's there now. I thought that I'd offer a variety package of what's available. I received pricing on a Viessmann unit and then went on to ask about something in the Takagi line. Well......that's when I got an earload from the supplier. "You can't use Takagi - they're water heaters not boilers!" 'What's the diff', I asked. Flame to water heat exchanger, units are rated for various MBH inputs. I figure, as long as the pump is sized for the load - all will be good. Well, there was no satisfaction from the supplier, so I emailed Takagi. They tell me that you can use the units for heating but that I do need to remember that these are water heaters, not boilers (What???!!!). Aren't we splitting hairs here?

Whatever I decide for the heating appliance aside, my question is about boilers vs water heaters. In my day, I always thought a water heater was a storage appliance with some type of heating application on the unit, (burner, element, etc,), while a boiler had minimal water capacity and required movement of water through the appliance while it was being heated. I appreciate that an on-demand unit is a bit of a different dog, but I still see it as a boiler in the larger sense of the word.

Have I totally come off of the axle here? Your collective inputs are truly appreciated.

Thanks



Canuck

Henry

Boiler certification

Boiler and water heaters are certified in Canada under CSA standards. There are some boilers (HTP and some combo units) that have both a boiler and DHW certification. You cannot legally instal a DHW unit for heating unless it is certified for heating. If it is a gas apliance, B149 does not permit it and your utility will tag you. Then, you also may have legal problems if another contractor detects the install later on.

Canuck_3

Doubting

I'm not so certain. B149 doesn't even have a definition for water heater and I can't see where there's any restriction on use. Both types of appliance are built in Canada under B51 code restrictions. Fuel application falls under B139 for oil or B149 for gas or some electrical code for electric models.

I'm not disagreeing here Henry. I just want to know where it defines what a water heater is (and isn't) and where the restriction for heating application comes in. Even in the new B214, there is no mention of this.

Can you tell me what section of B149 indicates non-use of 'water heaters' for heating application?

Anyone else out there want to dive in on this. The topic has really gotten under my skin now.

Zman

I think it is a duty thing

Henry is very knowledgeable on code north of the border.

To me it comes down to duty rating. Its not that you can't do it. I just won't function optimally and won't last as long.

There are many nice boilers that cost less than Viessman, but more than a water heater. Why are stuck on 2 extremes?

Carl

Canuck_3

It's the principle now

I'm not stuck on extremes - we'll probably be putting in a Weil-McLain on this project - but that's not the issue here.



When someone says to me something can't be used because...........whatever, and there's no back-up, I need to drill down and find out if we're all just following each other in circles. I don't doubt that Henry is knowledgeable but his code references don't appear to pan out. You're indicating a possible duty cycle problem, which may in fact be true - but we're all just reaching at what we've been told by others. I want to know where it says "such and such" can't be done.



If I want to use a 40 gal oil fired or gas or electric water heater as my primary heat source for a heating only system, where does it say that I can't. Likewise for a wall hung unit. What defines one as a water heater and another as a boiler? Is one exclusive of the other and are there restrictions for use? Who has regulated this and where is this documented?



It's down to principle now.

Zman

Best of luck

I wish you the best of luck with that.

There is a guy on the radiant forum that wants to heat his house with a hot tub. Why not?

Carl

Charles Johnson

Reliability

I wouldn't use the Takagi.  They have not been as reliable as a boiler in my experience.  Just look inside them, you will see 2 or 3 times as many components and wiring as you would in say a Weil Mclain Ultra.



Plus, I don't like copper fin tube heat exchangers.

Canuck_3

I'm just saying

Listen - I realize that there are some pretty kooky ideas out there and that some are just plain bad. But just like when our gas code used to outlaw bushings and now they don't (unless they're stacked) - when I have someone say that bushings aren't allowed - I'll direct them to the latest B149.



Right now - I just want to know who's the authority having jurisdiction on this topic.

Gordy

Money

ASME certification costs big money. If your making an appliance for DH specifically, and its selling why spend the money to get the appliance certified for heating use. If the buyer wants to apply it to non DH use then its another one sold anyway at the buyers risk. Hence your response from takagi.





A lot of the boiler, tank water heater, instantaneous water heater controversy has to do with efficiency of the units the system, and life cycle costs. Boilers specifically mod/cons will out perform a tankless in all facets because its designed for heating, but a tankless should have more longevity in a closed loop heating system verse a domestic environment.





Also look at the modulation capabilities of the two types mod/cons have sizing more specific to the loads of heating systems, and their on board logic heating system specific with dh capabilities. Not so with a most tankless units.



Tank type water heaters can be used for small loads, but again efficiency is lucky to see 65 to 70% let alone controls on board.





So in the end you get what you pay for. You can call it following circles if you like, but there are reasons for that. This has been discussed here on many threads. Just remember you will need a screaming circ. on the primary to get the tankless to work.



Gordy

Canuck_3

I can accept some of that

Life cycle, system efficiency and modulating controls are all extremely good reasons to choose an appropriate boiler over a water heater. If that's the answer, in the end, of why a water heater shouldn't be used in a heating application, then I'm fine with that. There's thought and logic in that argument.



If someone is going to tell me though, that I can't use a water heater in a particular application because the heating police won't allow it - I need more substance than that. Show me the code, show me the bylaw, show me something.



And I meant no insults in the 'following circles' comment. I've been in the business for over 30 years and have brought my four boys into it as well. I know full well that when they were green, I'd show them or tell them of things that I'd learned or experienced. Times change - and I hope that in their growth, they come to challenge some of the 'lessons' that I may have taught them instead of blindly following a thought because 'that's what Dad told us'.



Your all a bunch of fine guys here and that's the reason I came with my question - so that I too could learn something.

Gordy

ASME website

Brochure with Order Form

BPVC Listings in the Product Catalog

About the Code



The International Boiler and Pressure Vessel Code establishes rules of safety governing the design, fabrication, and inspection of boilers and pressure vessels, and nuclear power plant components during construction.



The objective of the rules is to provide a margin for deterioration in service. Advancements in design and material and the evidence of experience are constantly being added.



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Gordy

Henry

B149

It is simple. We have a definition of what a boiler is in the code. Then you have 4.2.1 which says that the appliance must be certified for the use. 4.2.2 allows the "authority having jurisdiction" to change its use. We made changes in the code to prevent some enterprising folks of using a heating boiler, changing the safety valve and installing same to provide domestic hot water.

matthewj

flow rates

Instantaneous water heaters are designed for high delta T. Because of their heat exchanger design they may not be able to get the BTU's into the water without forcing higher flow rates through that exchanger than they are designed for.  Not a recipe for long life. 

Canuck_3

Thanks to all - save the file

Along with the discussions in this forum and emails sent to me from other industry personnel, it all appears to be that water heaters are water heaters and boilers are boilers, but sometimes the twain can meet. The ability of one to be used as another is found through dialogue with the manufacturer. By example, Takagi does allow their units to be used as boilers - but with restrictions. I was directed to the file I've attached, during this journey of enlightenment. It has most of the info in a nutshell.



I'll know from here on in, to discuss application with the product manufacturer prior to assuming that their product is a catch all for any ideas that i may have.



Thanks again!

Zman

Thanks

Thanks for shaking the tree on this. It is always good to periodically check the assumptions we all make.I wish someone had done the same for double bubble insulation, non O2 tubing and a handful of boilers. It would have saved some headaches.

Carl