18 unit building oil to gas conversion - Advice needed

Brian Chilton_2

I just purchased a 18 unit building, currently it has 3 oil fired boilers around 125,000 btu each. Hot water radiators, all units are small one beds and studios. I pay for heat. There are 18 gas water heaters on each tenants gas meter, so they pay for hot water.



There are 3 chimneys, and because of windows/driveways/doors and decks, I think it would be easiest to use the chimneys for the new system as opposed to power venting.



I have been advised to put in  Burnham Series 2 standing pilot units, to replace each of the oil fired boilers.  We will reuse the existing zone valves that are controlled by each apartment's thermostat.



My question is does anyone recommend a more efficient boiler that would provide high reliability(it is not fun to get a no heat call from 6 tenants if one of the boilers goes down), and more efficiency than the series 2?  One person suggested the ES line from Burnham which would still chimney vent but is a little more efficient and can accept options like outdoor reset more readily.



I am about to buy the 3 standing pilot Series 2, but am having second thoughts. Any words of wisdom would be greatly appreciated.



Thanks all.

JStar

Boilers

The key to any long term reliability is the proper installation. I would definitely tie the boilers together, and stage them. Then, if one goes down, the other two will keep running, giving you time to service it.

Brian Chilton_2

Staging

Thanks for the idea to tie them together. I really like that idea.  Each boiler serves 6 units, and there are 3 chimneys, you might think of the building as three adjacent 6 unit buildings with a common basement.  Would you still tie them together if they are 50 feet away from each other?

JStar

Boilers

I would install a primary/secondary loop that they would all tie in to, even if so far apart. If it's all on one meter, and one bill, that will be the most reliable method of always having heat.

icesailor

Venting:

And depending on the size of the chimney flues, you could probably vent all three through the same chimney and have all the boilers together.

Why on earth would you buy boilers with standing pilots? I thought they were now illegal or soon will be. If you want efficiency, go with something with electronic ignition.

I think you need help with some more forward thinking installers. The ones you have spoken are either in the distant past, or you weren't listening to what someone may have said.

JMO

icesailor

Venting:

And depending on the size of the chimney flues, you could probably vent all three through the same chimney and have all the boilers together.

Why on earth would you buy boilers with standing pilots? I thought they were now illegal or soon will be. If you want efficiency, go with something with electronic ignition.

I think you need help with some more forward thinking installers. The ones you have spoken are either in the distant past, or you weren't listening to what someone may have said.

JMO

Brian Chilton_2

It was a clear

conversation - the thinking was a standing pilot would only cost "a few dollars a year" compared to electronic ignition. The series 2 can come with electronic ignition for a few bucks more per boiler.  The Elec Ignition is not a cost issue, it was passed over to increase reliability.



So then maybe the question is Series 2 electronic ignition vs ES2?

Tim McElwain

Each pilot costs about $100 to $130 per year to operate

How old are the oil boilers? Why not a gas conversion burner in each one giving you efficiency in the range of 80 to 83 %. What is the make of the existing boilers?

Zman

Mod/con

Have you looked into mod/con boilers. You can sleeve your existing flue and get far better efficiency than the other options you discussed. Assuming your existing boilers are sized correctly (has anyone done a heat loss?) ,You could run (2) 160,000 btu mod/cons and get fantastic efficiency. I don't see a problem with running 50 feet of pex to tie them together. I prefer the firetube heat exchangers in the Triangle Tube and Lochinvar boilers over the  exchanger burnham is running. They require less maintenance and you can use a much smaller circulator. I would look for a second opinion as soon as I heard the word "standing pilot" Is any one in the "find a contractor" section near you?

Carl

Brian Chilton_2

2 Burnham es2 boilers more efficent than 3?

Thanks all. I am going to replace the 3 monster oil boilers with 2 Burnham es2's tied together.

will use the existing chimneys, and line them. Will use the outdoor reset.  Hoping to save some $$ over the oil that is there , and I suspect that 2 boilers will be more efficient than 3 with the same combined total btu's.



I was told to wire them with lead/lag so they alternate doing work when the weather is not real cold.



Appreciate all the advice, I feel much better about this solution.



Brian

Zman

I would still do mod/con

If you have to line the chimney anyway, why not a mod con. The burnham you are looking at is a single stage.

 The idea is to match the load and run nice long cycles. For example 2 100,000 btu modcons with 5to1 turndown can fire at anywhere from 20,000 to 200,000.

2 100,000 conventional boilers can only fire at 100,000 or 200,000. This will result in short cycling and inefficiency.

Carl

CMadatMe

I'm with ZMan

Best investment is in the mod/con. The cost of the ES2's with the ODR cards and liners is going to be pretty close to the ES2's after adding the boiler staging control.

Brian Chilton_2

Modcon

Zman, Chris -

I was going to line the chimney with a standard aluminum liner, my impression was modcon needes stainless.

I was also more comfortable with the annual maintenance on the ES2's(none) compared to a mod/con. 

Initial purchase cost was also a factor, the ES2's are pretty inexpensive compared to the modcon's i looked at.

Having said that, I am going to go back and look at the mod/con's again.  The problem is, the new meter is being installed Thursday and the boiler's need to go in soon, we have to have heat on by 10/15.

So decison time is immediate.

Thanks for all your help.

BTW - am I correct in thinking there would be savings in running 2 boilers rather than 3?  I thought 2 would be ideal since it would provide some backup capability with cost savings. The other idea would be to put in one very large boiler.

CMadatMe

Mult Boiler

I would def go with multiple boilers. You can vent most mod/cons with poly propylene which comes flexible just like a stainless liner. Knowing the pricing I can't see condensing being that much more. The maintenance argument is getting old and in my opinion a false statement. All boilers require a yearly maintenance to make sure they are maintaining the efficiencies they can produce.

Brian Chilton_2

you guys convinced me - i am meeting with a triangle tube rep

He is going to look at 3 modcon singles to replace the existing 3 cast iron/oil monsters and also look at a cascade using 2 250 btu's tied together on a rack.



My concern is still reliability/cost of install/cost of equipment vs cost savings



If it is a 5 year payback or more, i don't think I can justify the additional expense.  The town where they are going has its own gas department so there is no money coming back for being a highly efficient boiler.



Thanks for getting me comfortable with the idea, not I have to see enough savings to justify the expense.  I asked for a ballpark on the rack mounted cascade, and it was a big number.

Zman

Good plan

You don't need the rack to cascade the boilers. You can keep the existing location and pipe them together. They will automatically cascade control.

To match your existing sizing, 2 -TT175 would be the closest. With the higher efficiency boilers you get more output.

Carl