Need advice on new gas boiler

JSRIII

The 50+ year old gas boiler went out last Saturday.  I have been researching replacements and am having difficulty.  The house is a 4 family with 1 studio and 3 one bedrooms.  The old boiler was covered with asbestos and the chimney is unlined.  There is a stand alone gas hot water for domestic water that is 2 years old.  I am told that most available boilers require a 6 inch flue pipe and the current hot water heater uses a 3 inch.  I was told to determine liner size, you take the diameter of the boiler flue and 1/2 the diameter of the second appliance, in this case, the hot water heater.  Therefore I would need a 7.5 inch liner or an 8 inch since I don't see 7.5 inch for sale.  Unfortunately, the inside dimension of the chimney is 8 inches so I am afraid that the 8 inch liner won't make it down the chimney.  Also, the few liner companies that I called can not come out until December.  This eliminates the initial Jomar, Burnham and Weil McLain boilers that were being quoted as they require a chimney.

So now, the contractor that I was leaning toward, is pushing the Budurus that can be direct vented, however, the cost is almost double the original 3 discussed.  The house has hot water radiators and it was estimated that we need a boiler in the 90,000 BTU range.

Any thoughts or suggestions would be greatly appreciated.  I have read that the stainless steel systems are better than the aluminum due to corrision.



The asbestos is gone so I need to move quickly on the boiler as it is getting cold outside.



Thanks

JStar

RE

You can't determine liner size based on flue size alone. It all depends on the amount of BTUH in total, chimney height and construction.

JSRIII

Here are the details

The boiler is around 90,000 BTU's and the hot water heater is a 50 gallon.  Not sure how many BTU's.  The chimney is brick with no clay liner and it is around 30 feet from basement to top of chimney.

lchmb

condensing

If you are concerned with the aluminum block, you could look at the Viesmann or Triangle tube (or the Helix which is displayed on the wall, never used one but) ..they have stainless HX. Although more of an investment I would also recommend getting rid of the stand alone water heater and going to an indirect. BTW, I install a lot of the Buderus and as long as the system is installed and maintained properly have not had a problem..

JSRIII

what about other manufacturers?

Wondering what other manufacturers make a direct vent gas boiler other than the Buderus?  The original Jomar, Burnham and Weil McLain were ruled out due to the chimney issue.  What else is available that can be direct vented?  Don't any of the companies above offer a DV boiler? 

CMadatMe

Heat Loss

How did they determine a 90,0000 btus boiler? Did they conduct a heat loss? Did they measure the rads and determine there capable output? Yes the others make Draft induced boilers. The Burnham ESC is an excellent choice for a cast iron boiler that is 85% efficient. The boiler also offers a simple plug in out door reset control for added fuel savings. I'm a much bigger fan of the Burnham G4 iron then the others. The design of the iron sections allow for a much lower return water temp then other cast iron boiler competitors and keeps the temps across the iron even. No hot spots that tend to fatigue others.



If your looking at condesning boilers then the Viessmann and Triangle are both good choices.

JSRIII

Radiator survey

The BTU requirement was determined by a radiator survey.  All radiators were measured for height, width, length, number of tubes and sections and style of radiator.

lchmb

The

only way to properly size a hydronic heating system is by a heat loss. Do yourself the favor and have this done or you may over size your system and lose out on savings..

CMadatMe

The Great Mirror

Agree with Ich. All the measurement of the rads do is give you the capable btu output of the emitters. This has no bearing on what the home needs. The only way to calculate that is to do a heat loss. Once we know the heat loss we can then thru the measurement of the emmitters calculate the water temperature we need the system to produce on the coldest day of the year.

JSRIII

Heat loss

How does one do the heat loss?  Is that the one where you measure all of the rooms, windows and doors?  We discussed that but it seemed easier to measure the radiators.  Do you only measure doors on exterior walls?

lchmb

Taco

has a nice program online that you can use to do a heatloss yourself. You will need your window and door measurements.