Oil-fired boiler options and sizing

BillCapeCod

Hi all.



First, thanks for this forum. I've learned a lot by doing some homework here.



I have bids to replace our ancient oil-fired boiler and tankless coil (natural gas is not available here.)



1100 square foot house on Cape Cod, with one bath, four people at most, and recently completed air sealing and insulation through the Mass Save/Cape Light Compact program.



I did my own heat loss calculation using the slant fin calculator and came up with 28,600.



Contractor #1 sized the boiler using the radiators, and is suggesting:

1: Burnham MPO-IQ 115 with IQ

2: Buderus 115 WS/4 w logamatic



Contractor #2 did a heat loss calculation, and come up with 30,000 and suggests:



Slant Fin Ec-13;



Contractor #3 sized using the radiators, and is suggesting:



Buderus 115 WS/4 @ with logamatic (as did contractor #1, at a different price)



All have offered indirect dhw options, which ill get to after I figure out the boiler (if that makes sense.). I'm planning on a 40 or 45 gallon.



Question 1: aren't all of these options these oversized?

Question 2: would these boilers require a chimney liner? (Contractor #2 mentioned this. I thought this was an issue with condensing boilers, but not these types/models?)



What do you all think of these options? Any advice, suggestions for additional homework/research, etc?



Thanks!

Eric_32

depends...

On the size and condition of your existing chimney. If the chimney is too large you will have issues with getting proper draft because the boiler could have a hard time getting it warm.

MA code doesn't require the chimney to be lined for oil or certain gas installs, but it does depend on the size and condition of your existing one if it should be done.

I would recommend a 3-pass boiler they tend to be more efficient than standard boilers. I have installed the Buderus with and without the Logomatic, many times and it would be my choice.

Robert O'Brien

Oversized

Yes, but since the smallest oil boiler is twice what you need, there isn't much alternative. I would consider a 115/3 , Biasi B10-3 or the EC3. Chimney lining is a good idea but may or may not be mandatory.

icesailor

Potable Hot Water

Ah, MassSave and their 8 hour heat loss home improvements classes.

If you think that you can heat the house and take showers for four people concurrently, you must like cold showers.

You better install a 40 gal, indirect to have adequate hot water or a smaller one to run hotter with a quality thermostatic mixer installed.

With a house your size, potable hot water is the hot load, not the heating system load.

The old IBR radiation and boiler sizing manuals had really high potable domestic hot water load calculations that were way over sized but you would never run out of hot water. My experience was that you didn't need to go that far.

The old dead heating sales-persons were always afraid of a cold house so always were liberal in their calculations. You never had a cold house.

The old dead plumbers and this soon to be joining them always have to deal with the "No Hot Water" syndrome.

If you have oil now, and you are on Cape Cod, you have a tankless heater with a boiler that is fired at well over 100.000 BTU's per hour. More like 150,000 BTU's. That is heating your house in January AND giving you adequate hot water. Which takes priority with the controls over the heat when needed. MassSave (and others) have moved you to a heat loss of 30,000 BTU's when you have a boiler that is fired at 4+ times what they figure, is not good thinking. Your current boiler is basically a big hot water heater for year around use. The heating of hot water is a side issue. You don't need heat in July but you DO need potable domestic hot water.

Your "Heater" types get a cold house call when it is cold and extremely windy. By the time they get there, the wind has stropped and you look foolish for a frivolous cold complaint. (Ask me how I know). But cold water is obvious to any competent plumber. A 30 or 40 gallon gas water heater is only fired at 35,000 BTU's per hour.

Ignore your Domestic Potable Hot Water loads at your peril.

icesailor

Boiler Sizing:

And if you go with the choices of Contractor #1, and you pick the first choice, price is a consideration of yours.

I would use a Weil-McLain WTOG-3 that has a tankless and install a 40 or 50 gallon electric water heater converted to a storage tank. It would not be connected to heat water with electricity, just from the tankless on the boiler.

There is always LPG but after my last experience with a Cape Cod LP distributor after the storm and they ran me out and wouldn't fill me up for two weeks, I reserve recommendations.

There's nothing wrong with the choices that have been given to you, just that there are other choices you should consider.

Get a price from a LPG supplier and consider a LP Mod/Con boiler with an indirect. You won't need to worry about a bad chimney if you have chimney issues and many of them do.

SWEI

summer hot water

Solar, anyone?

Jamie Hall

What you don't mention is

is this steam or hot water?  I would have to assume it's hot water, but if it's steam the only way you can size a boiler is by addinng up the radiation.  Heat loss of the structure is irrelevant.

icesailor

Solar Cost:

Solar Cost Anyone?

When asked, I always give choices with my prices.

#1: Oil boiler with tankless.

#2 Oil boiler W/Tankless and storage tank.

#3: Oil Boiler with Indirect.

#4 Triple pass oil boiler with indirect.

The choice is always between #1 and #2. Depending on how good a salesperson, it will be #2.

Cost is always the factor. \

In MY experience.

heatpro02920

How about propane..

First off if I was your contractor, I would be trying to talk you out of oil all together, not too hard when most of the properties are old and old boilers are normally accompanied by old oil tanks, and old owners that have paid $---.-- for their annual "tune ups"... But we will get back to that...



As far as oil goes, I would be selling you a {you must have forced hot water since you mentioned buderus already} Buderus G115ws {Riello burner and direct vented not chimney} with a Smart indirect {sized to your demands at 160 high limit}.. I would install an outdoor reset control and delta t circulators for each zone and the indirect with a priorit hot water zone control unit... I have A LOT of experience with this specific model and I have experimented a great deal {Have a lot in the field and 2 in my own properties}. I get them to run a little bit underfired with delavan protek nozzle and by adjusting the plates, I also install a tiger loop{I like them on riello burners}.. The efficiency is great and the output BTU is around 65K... You get long run times even being a little oversized and you can run a pretty low high limit {since your radiators are most likely oversized}....



So that is for oil and you would be very happy with that system, Im sure... But LP would be a better investment...



So for LP, I would recommend {if this is an option for you, Cape Cod Oil sells propane as do many other companies over there}.. I would install a Weil McLain CGi3 boiler, again direct vented with an outside air intake, and again outdoor reset with delta t circs, but NO indirect water heater, I would install a Rinnai RU80 or 98 depending on your needs on demand tankless water heater.... The initial cost should be less than the above oil system {even after running the gas line} , it should last longer, will NOT need yearly cleanings, and the price of oil and LP are very close per BTU, plus most companies give you your first delivery at a discount... You will not be using the boiler year round which I like and the tankless water heater will save you on energy bills and get you a tax credit....



So thats where I stand, I don't like a mod con for smaller heat loads at all.... I like indirect water heaters but I like tankless units a lot better and the cost is about the same... I believe in getting that boiler sized as close to your heat loss as possible, at your design day temp you don't want that unit to shut off... I got a call about a month ago from a customer that I installed a CGi4 for last year, she said the boiler only stopped running for about an hour all night {her son has a bedroom in the basement next to the boiler, so I guess he was counting}, and I asked "what is the thermostat set at", she said "70", I asked her what she told me she keeps it at when I did the install and she said she told me" 70", I asked what the temp in the house was she said "70" I said "great, that is exactly how you want it to work, and I explained about the heat loss and the outdoor temps" this did happen to be a night that may have been colder than the design temp, I remember it being about the coldest day in a while after a really cold week....



Now is this the best way to size something? I'm not really sure, it has worked thus far, and will save you the most energy, But I also remember a while back {I believe it was 1996} we had a cold snap in February that brought us to the negative 20's, and we had a lot of houses that would not go over 55-60 degrees, and a lot of frozen houses too from over worked systems quitting.... Which is why I normally do over size oil a tiny bit, I notice the duty cycle on the burner motors,transformer {constants}, and oil pumps are not quite 100% where I have seen gas boilers run non stop for weeks with out a hiccup {even direct vented ones}...



Now these are just my opinions and what I install 3-5 times a week, for gas I like buderus for systems over 70K and the Weil McLain CGi boilers for anything under, for oil I like Buderus for everything except steam of course which I will go with the Burnhams over most others sometimes a Utica Starfire 3, and for oil fired with a tankless {which is getting rare} I go with almost anything cast iron wetbase -- Utica, Weil McLain golds, Williamson, ect just depends on the install {piping, sizing, layout, space, venting, ect} , availability, and the budget...



What ever you decide I would get a contractor that is comfortable installing Direct vent, ODR and delta t circs, as well as adjusting the firing rate {if you go oil} to match your demands... That handful of items will save you their additional costs the first couple years if not less, I notice around 10% just going Direct vent outside air, and correct sizing with the delta t circs and an ODR should be good for another 25%, then put on top of that another 20 or so % savings going with a condensing tankless over boiler fed tank... Even with your small heat load you should see $800 annual savings easily...



Good luck, I know its a lot of info and potentially a 30 year decision...

icesailor

Heat Types:

Jamie,

This is Cape Cod. It sounds like your average small Cape Cod ExpandoRanch/Cape built between 1960 and yesterday. I doubt that there was much Steam installed on Cape Cod during this time frame. Anything is possible, but my comments on Potable Domestic Hot Water still apply. It isn't the heating load that is the problem with these mini-haciendas, it's the hot water in the shower.

There is no wrath like a woman scorned or a woman in a shower with shampoo in her hair and no hot water. When that happens, they don't call the "Heater", they call the Plumber. The Plumber gets the ear blast and has to fix it.

BillCapeCod

Follow up questions re: DWH, oil options, propane

Thanks for all the feedback. I appreciate the help. This is a hot water system, not steam. I should have mentioned that in my first post.



1. I'm not sure I understood all the comments about the DHW. Is the point that I do or do not need to take a 45 gallon DHW tank's need into consideration when sizing? I know I can't completely disregard it, but one contractor took the heat loss calc and said, "we need to add the DHW to that, so you need 100,000." Maybe he was simplifying for my benefit, but with priority control for the DHW zone on an indirect, this isn't precisely correct, is it?



2. Does anyone have any other specific oil-fired options to suggest, in addition to the Biasi (I'm trying to find someone local who installs this brand.)? Any explicit preferences for the systems I have listed?



3. Lastly, I'm open to the idea of propane, but I had a hard time getting the math to work. The improved efficiencies seemed to be offset by the BTUs per dollar? Is the point here that in addition to those factors I need to consider the addition benefits of better sizing options for my relatively small heat load, on-demand for DHW, other?



Thanks again for all the help.

heatpro02920

Hello Bill...

OK first as for adding btu's for DHW, Some people do some don't, I don't normally UNLESS the boiler is so small that is does not meet the needs with the tank, where using a larger tank can offset this, sometimes it is not an option... So to answer the question IMO, NO don't add for DHW, use a priority zone control that will wait until your DHW needs are satisified before applying heat to the space heating....





Next would be recommendations for the oil boiler, I hate to repeat myself but look at the buderus g115ws/Riello direct vented, down fired with a protek nozzle and use delta t circs with an ODR aquastat control {hydrostat 3250plus will take care of the lwco too}.... for oil it is IMO as good as it gets..



Now again for Propane, you are saving more than the combustion efficiency {actually the oil and gas I mentioned are around the same combustion eff., I would stay away from a mod con if I were you}... The install should cost less, the yearly service will be less, the sizing will be correct, and with a Rinnai condensing tankless you will get the rebate and save quite a bit on DHW costs, plus allow the boiler to stay off all summer extending its life... I install a ton of the WM CGi, and direct vented with an ODR and delta t circs, you get the most out of them with the smaller heat loads... I have even used them for larger heat loads with multiple units on a cascading control....



I would seriously investigate the propane option BUT by far the most important thing to find is the contractor that is going to put it all together the rite way with your interests in mind....



How old is your oil tank? that is normally the deciding issue between oil vs lp, if you are going to need a tank within 10 years than go lp if your tank is brand new than go oil....



Also I would want the apliance either way to be direct vented, use the chimney for something else some other day, maybe an aux. coal stove....

icesailor

Direct vent Oil:

Where I work, as of a few minutes ago, it is still gusting to over 37 MPH with average wind speeds, 22 to 28 MPH. It gusted to well   over 65 during the last two days.

Direct vent or "Balanced Flue Oil" has been a complete disaster for anyone who installed it. Finally being replaced by Power Venters.

Jesus Christ was a carpenter. He could not stop a French Door from leaking  in an East facing location in the rain. If He was a "Heater" installer, he wouldn't be able to make a "Balanced Flue" burner work.

Propane companies have a sliding scale rate based upon heating and hot water use as the lowest. Make sure that you get a quote based  on the lowest rate.

When quoting, I give multiple prices and options. The lowest might be a steel New Yorker, as low as you can get. To the soup to nuts. I don't do New Yorkers anymore. I wouldn't want to have to work on it. But it might be surprising to some about how many want the beef stew made with sirloin tips but would rather pay for canned chicken soup or even chicken broth.

So, I see a direct replacement oil to the soup to a chocolate mousse install. Where you end up will be what you are willing to pay for. I don't know where you live on Cape Cod, but gas will be close by in the future. If you go with LP, you just need to be sure than your boiler can be converted to Nat Gas.

The town I live in is notorious for passing arbitrary and capricious regulations designed to help some earthy crunchy constituency. Usually at the expense of the less wealthy. I have a new 12 YO home with oil. My oil tank must be replaced with a double walled tank. An inside steel tank that is in my warm cellar, 10' from the boiler on a concrete floor. The cost of replacement is stupid. If I sell the house, I have to change the tank. There is Nat Gas in the street in front of the house, 500' away. I will replace my oil burner with a Carlin EZ-1 gas before I replace the boiler. I won't get more money for the house if I switch to a gas boiler. I will put another LP tank beside the one there for my gas dryer. I won't live long enough to see a payback.

What I see is CHEAP when given the choices of equipment and price.

If you shop for used car at the dealerships on Willow Street, you probably won't be going to the Mercedes Benz.Volvo, BMW dealership at the rotary. A CGi LP new boiler may not be as efficient as the boiler you now have if it was really spruced up.

What you buy will depend on what the price of the equipment and the installation cost is. And where you can vent it.

BillCapeCod

Thanks; any suggestions on local contractors?

Thanks; that helps a lot.



I have started doing some research on local contractors who will bid on a propane system. Not having too much luck so far, but I do have a few leads. If anyone has suggestions, I'm all ears!

heatpro02920

Cape cod is tough, lol

Did you try the find a contractor link on the home page?



Make a list of what you want and get a few prices for the smae equipment so you can compare apples to apples, also ask to see pictures of work they have done similar to yours, I know I have about 200 pictures of systems I have done in my phone and my techs have pics too, when you take price in your work you will have pictures to show it off...

SWEI

solar cost

reliably pencils out for DHW here.  Space heat during shoulder seasons sometimes.  Meeting 100% of design load using active solar is just for rich guys.  The smart ones supplement with LPG, wood, or both in mid-winter.



My suggestion was a summer alternative to oil.  I have seen this work quite well in places with higher summer occupancy.