Boiler sizing on a gas conversion

homeownerheet

I'm in the process of converting two systems from oil to gas (hot water baseboard) in my two-family. I've had a few different quotes and have decided to move forward with a someone who has been in the business for a while and has good reputation. Planning on installing a Burnham ES2 (105 btu) with SuperStor indirect hot water for each unit.  I'm happy with the equipment choice and he'll also be putting in a liner for the chimney.  Each apartment is about 1100-1200 square feet. The house is 100 years old with blown-in cellulose, newer windows, and no insulation in the flat roof.



My wife and I live on the first floor and the place is pretty cozy. It's a one zone system, but we will likely be adding an additional piece of baseboard in a bedroom that currently has no heat.



The second floor unit has the problem of having no insulation in the roof and the back half of the apartment is under-radiated(?). It is also currently one zone of baseboard, but we are adding baseboard in 3 rooms.



My question is about the sizing. My heating guy did not do a heat calc but had me measure the rooms and baseboards and had me send this information along to someone who ran the heat calc off those numbers. I've attached a page to this post (Zone 1 is actually apartment 1. Zone 2 is actually apartment 2).  The heat guy says the 105s are the way to go and that a smaller boiler (70btus) would be too small for heat and hot water. In looking at the heat calc, my untrained eye wants to say the 105s would be oversized for, at the very least, the first floor apartment. All three quotes I got suggested 105s. I'm assuming I must be missing something. I've read this board enough to know that heat calculation as done isn't the most precise. I just want to know that the boilers will be running as efficiently as they should. Any opinions? Thanks for taking the time.

CMadatMe

My Honest Opinion

Get a new heat loss done of zone 2...I don't know what climate you are in but from that loss I would say the north pole.  That's 50 Btu's a sqft.



The boiler is oversized.

Ironman

2 Boilers?

Are you saying that they're proposing 2 105kbtu ES2 boilers? That's about 180kbtu's output. Why would you need that much when the total for both apt's was 67k?



I have to agree with Chris on the calc. for the 2nd zone. Something's off in the figures.

CMadatMe

Existing Baseboard

Could you please provide us with the existing footage of baseboard in the 1st and second floor apartments. I would like to compare the footages in each room to the loss you provided. Your installing an ES2 and you mentioned nothing about the outdoor reset card.

If I were in your shoes I would recalculate that loss and use the money I was going to spend on the oversized boiler and go to the local HD and purchase some insulation for the attic. Calculate the loss as if you have already put the insulation in the attic. The insulation is the best investment. Lower the loss, lower the boiler size.



In your case an indirect may not be the best avenue. Due to the small DHW load I'm thinking a condensing boiler such as the Trianlgle Excellence may be the best route for this application providing I can limit its rate of modulation in the heating side separate from the domestic side. I'm a Viessmann guy and generally would recommend that boiler but as of today we do not have a combi unit here in the US. There are alot of great guys here that install the Triangle product that would be able to provide more insight into the boiler then I.

RobbieDo

Seems Large

As said in previous posts, I would insulate if possible. I would also have another heat loss calculation done, that is a lot for a small area. I don't install Viessmann or Triangle either but Trinity NTI makes a nice combo unit, installed many of them with great success, has to be installed properly and serviced annually.

homeownerheet

Follow up

Thanks, everyone for the helpful input. Yes, ideally I would insulate the roof, but there is no attic. The only way I've seen to correctly do that is by putting on a new roof with polyiso. There are loads of guys around here willing to blow cellulose into a flat roof. They'll also tell you it's not recommended due to ventilation issues. I'm choosing the conversion over the roof with the hopes of doing the roof in the next year or two. It's an old BUR that probably needs to be done anyway.



I'm in Boston and started this whole process thinking about the Burnham products because of National Grid's rebate program. I've seen the Triangle Products and others mentioned on this board but haven't researched them much because of what I assumed (maybe wrongly) to be higher costs, and the guys I've talked to haven't mentioned them. I took a quick look at the Triangle Excellence and it looks like an interesting possibility.



What everyone has said about the ES2 being oversized and excessive makes complete sense to me. I'm just a little baffled because the 3 heat pros that came in they all recommended essentially the same solution. The only difference is that one guy suggested using two Burnham Alpine 105s. I guess they're just basing this off of the existing oil boilers? I was interested in the outdoor reset for the ES2's but thought I might be able to add this later. All the systems for the two apartments are separate and I'd like to keep it that way unless it makes too much sense not to.



Chris, I've pasted the the information on rooms and baseboard that I sent to the guy that did the one I've posted. It certainly sounds worth it to have someone why knows what they're doing (I'm talking about my own lack of knowledge on this) take another look. I do know that my upstairs tenant did spend twice as much on oil as me with a nearly identical setup (except for much less baseboard). Thanks again to all who have posted. While the details of this stuff keeps me awake at night, I'm glad it's out there.



Eric





Here are the measurements for the first and second floor units. All windows are Harvey double-pane windows (Massport). The walls have blown-in cellulose. There is no insulation in the ceiling/roof (flat roof).



1st floor unit



Front Hallway

9' x 3' x 9'

(L x W x H)

Baseboard 1' (convector type)

Front door



Living room

16' x 13.5' x 9'

Baseboard 12'

4 windows



Dining room

16' x 13.5' x 9'

Baseboard 8'

3 windows



Bedroom 1

13.5' x 8' x 9'

No heating

1 window



Kitchen

16' x 12'2" x 9'

Baseboard 12'

1 window



Mudroom

7' x 7' x 7'2"

No heating

1 window & rear door



Bathroom

5'8" x 8'5" x 9'

Baseboard 4'

1 window



Bedroom 2

12' x 6'10' x 9'

Baseboard 6'

1 window



2nd floor unit



Living room

16' x 13.5' x 9'

Baseboard 18'

4 windows



Front Office

10' x 7' x 9'

Baseboard 5'

1 Window



Dining room

16' x 12' x 9'

Baseboard 12'

2 windows



Bedroom 1

13.5' x 8' x 9'

No heat

1 window



Kitchen

13.5' x 12'5" x 9'

Baseboard 24" (Convector type w/blower)

2 windows



Rear Hall

7' x 3' x 9'

No heating

rear door



Bedroom 2

13'5" x 8' x 9'

Baseboard 24" (Convector type)

1 window



Bathroom

5'10" x 8' x 9'

Baseboard 24' (Convector type)

1 window

CMadatMe

Based on All Your Information

After looking at everything including the Mass rebate which is attached, my feeling is that you should be looking at a 96% boiler which has a $1,500 rebate and a on demand tankless with a energy rating of .95 that gives a $800.00 rebate. That's $2,300 bucks vs the $900 bucks you get for the ES2 and the indirect.

Get some more estimates and each should be accompanied by a heat loss. I would get rid of the existing baseboard and install hi-cap board that will fit the same footprint. The board could be replaced over time as you would not have to touch the existing distribution system after being field verified. This allows you to take the full advantage of a condensing boiler for heating. I would be looking at a Viessmann Vitodens 200 WB2B-19. As of today there are only two boilers to the best of my knowledge that hit the 96% mark. Viessmann and Lochinvar. Viessmann is down the street in Warwick RI. The only issue I have with the Triangle PE110 is that it's oversized but if I can limit its modulation then it's a good way to go and still gets you more of a rebate. Hopefully some triangle guys can give you some feedback on the PE110 as it relates to it beging oversized on the heat load.



Find the contractor that has a plan and gives you options. The above are just  options. You could keep the ES2 sized properly and do the same with the board as well with the Triangle. I would add the ODR card now to the ES2 as it is worth 200 bucks on the rebate.

You should consider yourself lucky with the rebates Mass offers. I'm in NY and we only get 720 on a mod/con. The ES2 is only worth 350.

Tim McElwain

You can thank

the Gas Network for those rebates. Companies working together to make things more efficient and yet still sell their product which is GAS.



Good info for that customer Chris thanks for your input.