New Gas Fired boiler

[GeoVancouverBC]

Looking for some recommendations for a new gas fired boiler with cast iron rads in an old house in Vancouver, BC (2400 sq. ft,soon to be insulated). I love the heat from the old cast iron rads. Not sure if I want a condensing system since I only see negative comments about the number of service calls required but then again, maybe it's only the unhappy owners writing in and that happy ones don't write in to share.
Some brand names that I've heard a lot about: Viessmann, Buderus, IBC Technologies and Burnham.
Could someone recommend some reliable condensing high efficiency models and some better low tech models.
Thanks for your time.

[meplumber]

I have done a large number of Viessmann Vitodens condensing boilers with large cast iron rads and they work perfectly together. There are several things that have to be done in the near boiler piping to make the marriage work, but it is basic hydronics and is not hard for a true pro.

I strongly urge you to consider going with a condensing boiler. The large water volume of the system combined with the outdoor reset will make a comfortable and efficient system.

Good Luck.

[Maineiac]

My vote is Viessmann condensing and proper near boiler piping and trim. And for God's sake a LOW WATER CUT OFF

[Wheelbaron]

There are several good condensing boilers out there, the important thing is to find a good installer, don't be fooled by a flashy sales guy, ask to talk directly to the chief wet head that will be installing the system. He may not be that great at communicating with customers(he is an installer, not a sales guy) but you should be able to tell quickly if he knows his stuff. Then let the sales guy pitch the product.

[BadgerBoiler MN]

"My vote is Viessmann condensing and proper near boiler piping and trim. And for God's sake a LOW WATER CUT OFF ."

A low water cut off (LWCO) is only required on commercial boilers and those residential boilers that are installed above the radiation. If you use a Viessmann you should know that they employ a flow switch and a pressure switch, making a LWCO redundant. Whether the Viessmann is the right boiler for your particular applications should be decided on its features and benefits, but first on its size.

Sizing any boiler to the load is the first and most important (if not neglected) chore for any heating professional. Those who do not offer a heat load analysis before installation should be instantly eliminated from consideration. This alone will make the qualified ModCon installers list quite short in most areas of North America.

The modern condensing high efficiency boiler is a perfect match for old cast iron radiators as all modulating condensing boilers now incorporate outdoor reset. If the boiler is properly sized to the load and the reset is set to the design temperature for your particular area, the comfort of your home will increase while the fuel bill will decrease as much as 75%!

Negative comments about condensing boilers are nearly always from the misinformed and various DIYers who bought products on the Net and installed them without the benefit of proper heat load analysis, tools such as combustion analyzers, training, experience or due diligence (unfortunately professionals sometimes fall into this category as well).

This link should help you as you try to sort out the many condensing boiler choices and contractors who install them. As suggested it is more about the installer and his support system than the appliance.




http://www.badgerboilerservice.com/boilerchoice.html

[BadgerBoiler MN]

By the way, Viessmann and several other condensing boiler manufactures do NOT require primary/secondary piping for application that will not restrict flow, such as your typical single zone gravity conversion e.g. cast iron radiation system.

The pressure drop through such systems is so low as to be nearly immeasurable and present no flow restriction to the boiler making a second parasitic circulator redundant and wasteful at once. The other caveat for old radiator systems is the possibility of dislodging rust and other bad stuff (easy is you over pump with a P/S). This can easily plug up a Giannoni type HX such as the Vitodens, Munchkin etc.

The simple answer is a good flushing and a "Y" strainer or Callefi dirt separator. A hydraulic separator can be very useful where P/S piping is required or beneficial but this is not the case in most cast iron applications.

Cast iron and condensing boilers are a perfect match only outperformed by radiant floors or ceiling and perhaps in combination with properly (over) sized European panel radiators.

If you can't find a person to properly size or pipe your new modulating condensing boiler, find an independent factory trained designer to right a specification and let it out to bid to a good mechanic.

[chuckcrj]

Posts 5 and 6 are very good advice.

[BadgerBoiler MN]

Thank you kindly.:grin2:

[jimrorerk]

+1 for Viessmann

[LKJoel]

viessmann make a great boiler, I have had terrific luck with the Weil McLain Ultra series boilers, they work well, and install easy. I know people will say primary-secondary piping is not required, but it makes for such a nicer install, with far less head-aches problems and call backs. My advice is to find a contractor who will spend the extra time re-piping your system to properly suit a high efficient boiler. Also, have they run an outdoor air sensor, outdoor re-set with a high temp system and a condensing boiler, is the only way to go

[BadgerBoiler MN]

Weil McLain knows that minimum flow is required in low-mass heat exchangers and thus threatens no warranty if P/S is not used. This is why (even though I have had great luck with them) I will not use Weil McLain Ultra, SlantFin Bobcat, Buderus GB142, where P/S is obviously a waste of time, energy and pump.

By contrast, Burnham Alpine, Crown Bimini, HTP, IBC, Lochinvar Knight, NTI Trinity, Triangle Tube Solo and Viessmann Vitodens recommend, but do not require, P/S thereby attracting the professionals that can do the simple math required to size and adjust a pump and/or a differential by-pass valve.

For cast iron radiation P/S is simply a waste and one of the main factors I use when specifying a condensing boiler for and older home with perfectly good cast iron radiators.

Naturally a contractor must follow the manufacturers installation instructions, thus choosing the right contractor and he, the right boiler is essential.

All condensing boiler are better suited for cast iron radiators than conventional boilers, always doing a better job providing comfort and fuel savings.

[LKJoel]

Weil McLain knows that minimum flow is required in low-mass heat exchangers and thus threatens no warranty if P/S is not used. This is why (even though I have had great luck with them) I will not use Weil McLain Ultra, SlantFin Bobcat, Buderus GB142, where P/S is obviously a waste of time, energy and pump.

By contrast, Burnham Alpine, Crown Bimini, HTP, IBC, Lochinvar Knight, NTI Trinity, Triangle Tube Solo and Viessmann Vitodens recommend, but do not require, P/S thereby attracting the professionals that can do the simple math required to size and adjust a pump and/or a differential by-pass valve.

For cast iron radiation P/S is simply a waste and one of the main factors I use when specifying a condensing boiler for and older home with perfectly good cast iron radiators.

Naturally a contractor must follow the manufacturers installation instructions, thus choosing the right contractor and he, the right boiler is essential.

All condensing boiler are better suited for cast iron radiators than conventional boilers, always doing a better job providing comfort and fuel savings.


I wouldent ever call primary secondary piping a waste of time, but I see what your getting at. I prefer PS piping, it really is a better way to go, but have had no warranty problems from WM on systems installed with out it

[BadgerBoiler MN]

Weil McLain says you will have a problem, if you have a claim.

How does P/S improve your system? Why is it "a better way to go"?

[Maineiac]

Quote
#5 Today, 07:21 AM
BadgerBoiler MN
Professional Member Join Date: Jun 2007
Location: Minneapolis, MN
Posts: 476

"My vote is Viessmann condensing and proper near boiler piping and trim. And for God's sake a LOW WATER CUT OFF ."

A low water cut off (LWCO) is only required on commercial boilers and those residential boilers that are installed above the radiation. If you use a Viessmann you should know that they employ a flow switch and a pressure switch, making a LWCO redundant "


Not in Maine. LWCO's manditory. many boilers do not have pressure switches some have lwco's built in. Fact is it is a good idea IMHO.

[meplumber]

A LWCO is required, not only in Maine but in other states as well.

Badger, you need to realize that primary/secondary and hydraulic separation are similar but not one in the same.

Viessmann uses a low-loss header (hydraulic separation), Buderus uses their close coupled pump station(mix of the two), HTP recommends closely spaced tees(injection/pri/sec). As previously stated, the installer is the key to all of this. Find a good wet head in your area and trust his experience. A lot of his product selection may have to do with availability.

A system like this requires proper pump sizing. The boiler side circ and the system side circ or circs. I prefer to size the boiler side hard and the system side use a vari like the Grundfos Alpha. Just my preference.

Good Luck.

[GeoVancouverBC]

Thanks for the information and advice.

[BadgerBoiler MN]

"Badger, you need to realize that primary/secondary and hydraulic separation are similar but not one in the same."

Actually they are one in the same. How you get to it is another matter as you correctly point out. I have used all the common strategies and find two pumps unnecessary in most single boiler applications.

One should stay with the familiar if he must and follow the manufacturer's recommendations (especially if they affect warranty).

It pays to keep in mind the fact that all pumps are parasitic; two pumps, two parasites.

As for LWCO; all condensing boilers do have a pressure cut off switch and most measure delta T along with stack temperatures. LWCO on low mass residential boilers is not necessary but evidently religion/code in Maine. This is how superstition gets in the way of good science and statistics, though I admit I use a LWCO on every electric boiler I install, commercial or residential.

[2old2rock]

I'm not a boiler expert here like these other guys, but I would at least take a look at the Navien Combi-gas.

[genduct]

Thanks for the education!
I am inclined to agree a little more with meplunber regarding P/S
Seems to me injection P/S, with its small ( usually on board like Quietside?) pump the best bet since you won't be trying to shove all that water through the boiler.

Meplumber will you email me using my profile and Morgan, if you don't mind, I would like to understand some of your remarks as well

Mike

[BadgerBoiler MN]

All what water?

If you are unwilling to do the math, then P/S is for you - and the only reason some manufacturers mandate P/S.

This Viessmann system was installed - with their blessing - using the onboard pump with a internal three-way serving the indirect. Multi-zone baseboard with prioritized indirect and only one pump! Imagine.

There are no valid technical arguments for P/S on properly engineered single boiler hydronic systems.