Hot water heat and indirect water heater

[jmoar5]

I currently own a Burnham brand boiler that is a 240,000 BTU input. The house is large and i have been told that it is adequate. I am going to add an indirect water weater to the unit and have been told several different ways of doing it. I need to know what the "best" way is and what will be the most beneficial? Do I need it to be on a priority zone so the heat to the other three zones temporarily shuts off while this tank requires heat? Does it need it's own Pump or can the B&G pump i currently have be used? DO i need some type of circulator added? Any help would be fantastic.

My other is issue is what are the benefits to upgrading to a boiler with a modulating burner. I believe that it basically varies the input as needed and have been told it is the best way to go. Should i upgrade to a 90% efficient unit? What are the top brands in the industry. I always though Burnham was one of the best.

Please help a dummy before i spend some huge moola!!

[GradyWhite244]

The best way is to determine the heat loss of the house before adding the indirect. If the boiler has enough reserve capacity, you do not need to put the tank on a priority zone.
Yes it does need it's own circulator.
If your existing boiler is in good shape you could likely save a significant amount of money by adding an outdoor reset control. This modulates the boiler temperature with the outdoor temperature.
Upgrade to a 90%? Depends on how efficient your existing boiler is. Burnham doesn't make a 90+ that large. Buderus makes a wall hung 90+ up to 198,800 btu/hr input. Weil-McLain also makes 90+ boilers up to the the size you need but they seem to have recall after recall for one thing or another.

[jmoar5]

Can you explain in simple terms what a circulation loop is or does? I don't seem to be too clear on it?

Thanks so much

[jmoar5]

I am also wondering about the 90% units? My boiler is 1976 vintage with a standing flame pilot. If i went to a 90% unit wouldn't i need a smaller unit? What would the efficiency of my unit be?

[hydronicsman]

That is a big 'un boiler! Must be a BIG house!

At 28 years old, yes, I would look at a new unit for higher efficiency and peace of mind.

The smart thing to do is this: If the boiler needs to be that big (and I would do a heat loss calc to be sure) and it really needs to be that big ( I know, I've said it again) then I would do multiple boilers, staged. With gas, there are so many options in 90+ units, and controls to do this.

The reason you don't find too many monster 90+ boilers is that it is not intelligent, and it is wasteful to have one huge boiler running zones in a residential application. If only one or two zones call, the dumb boiler doens't know this, it tries to ram it's mega BTU's down the pipe. Short cycles ensue, and fuel consumption soars, and the equipment dies an early death. Modulation helps, like with the Munchkin 199M or the 399M, but when you have a bunch of zones, the things will modulate too much. Equipment design is key.

Modulating or not, if you are looking at loads over, say, 180K+ it really makes sense to split up the boilers and stage them so that the powerplant(s) can match the load. This is especially good for the gonzo indirect water heaters used these days for the human carwashes people "have to have".

When you do the load calc, and you find that your boiler needs all of the BTU's it can put out for heat, then you must prioritize the indirect. If you find that it is bigger than the heat loss then I would prioritize anyway to be sure all the available BTU's are going to the indirect for best recovery.

Always put the indirect on it's own circ. The flow requirements are sometimes different than the heating circ's. You do not want to wait for a zone valve to open, turn on an end switch, then start the boiler (maybe). You want that boiler to instantly start, and begin to make recovery on the hot water. Piping and circ is usually bigger than typical 3/4" pipe for proper flow to the indirect.

[Edited by hydronicsman on 03-12-2005 at 08:25 AM]

[beenthere]

Like the others, do a load calc before just getting a new boiler.

We haven't had the extreme modulation jumping with the Ultra that hydronicsman said about the munchin.

Peerless had that also with their mod boilers.

We always prioritize an indirect.

[johnsp]

If you've done any insulation improvements like new windows, doors, siding and attic insulation, you might not need that large a boiler. I would go with a Munckin or WM Ultra if you still need over 200K BTU's. You should only need the full output if all zones where calling for heat at the same time. With such a large boiler, you'll heat an indirect quickly on priority. If you don't go modulating, look at an indirect like the Ergomax, Turbomax or Dunkirk Artesian. Use the indirect as a buffer tank for when only the smaller zones call for heat.

[jmoar5]

Ok, Here's the deal. I have done a huge amount of insulation upgrades in the home. The interior now has all R10 triple pane widows, my attic insulation is up to about an R40+ and the exterior has been covered with 3/4" of concrete stucco. I'm pretty darn tight and in good shape at this point. I'm perplexed as to why no one has offered this wisdom of a heat caluclation? How is it figured? There is really no way of adding an additional boiler to the existing home unless it went in the same room as the other. Perhaps i need a much smaller boiler anyhow according to this info? Is there a charge for a heat calculation? I have a bi-level type home with a third level over the garage where the master bedroom is. Each floor has its own zone. The square footage of the home is approximately 4200. Big, but not overly huge as I may have portrayed. I'm happy to spend the money I need to in order to make this the best situation. I've done a lot over the past 6 years in tightening it up and want to spend another 20 years in this house. Money is tight, but I wnat to doe what's right and makes sence, not what's cheap.

I appreciate all your help, but it appears i need more, possibly more defined, input to do this right. Thanks!

[jmoar5]

I should also like to add that the larger (80 gal) indirect tank is for a bathtub that gets used nightly by two kids and a wife. It hold 120 gallons filled. We certainly don't fill it anywhere near the top, especially with a standard 50 gal gas tank at present. We just want to have enough water for the tank at all times. Two baths in a rwo with kleen water and possibly a shower or doing dishes would be a dream!

[tinknocker service tech]

i agree with hydro
with the size af your and all the improvements you have made it makes sense to pull that old war dog out the 27 years old it might only be about 70 percent effecient and at that btu factor burns a lot of fuel with 1 or 2 zones calling, inderict heater in the best way to go in the case i have one and never run out of hot water and have never had a complaint from any one . twin two 140,000 btu two gether and have them cycle as needed for the btu you need when you need it. in the long run you feul bill should be less. the water heater should have it own circulator and be on priority with most inderect it takes about 15 to 20 minutes to recover you will never feel it in the temp of the house

[hvac-tech-lane]

What is your fuel source? I assume its gas. But assumptions can cost.
Have you had a combustion effeciency test done on your current boiler?
You could do your own heat loss calculation with the software avaliable at the top of this page it's a great and easy program.You can download a trial version to check it out and then buy a one time use for a very reasonable price. I would also want my contractor to do his own to double check. search this site for; load calc and manual j, and read up you will get the best education money can buy for free.

[beenthere]

He currently has a 240,000 btu boiler, with all the improvements he's made, doudtful he would need 2 140's to do the heat, and domestic.

Call around and find a contractor that will do a load calc.

In some areas they are hard to find.

[johnsp]

Checkout the software for sale on this site. Or expect to pay for someone's time. I'm sure you'll come in under 200K BTU's even with indirect on priority. Get a single top of the line 90% eff modulating condensing gas boiler like the Ultra or Munchkin. No economic sense in getting 2 boilers.

[hydronicsman]

I've see 4 Munchies tied together, cascading controls, etc. My fear is that if this guys load is really over 200K, and only one zone calls, there is not enough turn down ratio on the bigger single Munch or Ultra.

Hey, who knows which way to go until we know what load we are talking here. If he wants a 120 storage tank, he will need 240K to make that baby recover decently, along w/ the big piping, etc.

I liken multiple boilers to putting on heavier clothing as the weather gets colder. Modulation sure helps, but has limits...

[beenthere]

I know what you mean.
He said his bath tub holds 120 gals, I don't think he meant he wants a 120 gal indirect.

I'm not well versed on the munchin.

An Ultra can mod down to 20%.
A 230 would give him a min input firing rate of 46,000.
And 230,000 max input gives ample ability to recover an 80 gal indirect.

But he needs a load calc done to know what he really needs for his house..

[hydronicsman]

I know, I goofed on the gallonage-my wife was rushing me out the door, and the kids were screaming..

80 gallon tank along with a mixing valve would be near impossible to run out of HW. Ought to have at least 180K net to supply it.

As more facts come in about the posters house, it's looking like the load may indeed be lower than the present boilers capacity. I'm going to revise my opinion

[tinknocker service tech]

first i stand corrected tow 120,000btu is what i meant sorry.a load calulation should be done since we are guessing about sizeof system. going with what we know he has 240 now and dont remenber the square ft so lets just 3500 for the hell of it. is it to big or small woh realy knows mow we add and boiler mate or any other brand 80 to 120 gal depending on # of baths and showers he has mow we have with out any books in front of me lets say we need 100 to 150,000 btus for the amout of gallons per hour he needs and pipe sizes from 1in the 2in for circulation. so with all this in mind. lets say you need 200,ooo btu for the house since the odds on all zones calling at once are slim cut the down on the water heater btu to 50,000 we are at 250,000 btu. now this is off the top of my head and no real facts in front of or charts to go by. just talk and not edged in stone by a long shot ok. i deal with wielmclain so this what i am going to use for now. i need a total of 250,000 btu on a real cold day and water heater usage take but only 100 to 150 on a hot day for hot water only. since most boliers or biger than what is realy needed take two 125 boliers with a twinnig kit to cycle each as needed to main tain temp so not to have to use btus that are not needed. this is only an opinioun and to me makes sense for certain houses is this house one of themwho knows. get a load calulation and a good contractor and let him tell you the best way to go because we are all just guessing and dont know.

[jmoar5]

Thanks for all the help. One small thing that i'm not getting at all. WHen you say i sould have the indirect tank on it's own circulator, does that mean that it needs a complutely separate circulation pump? I think that is what is being said. So i'm assuming i need a separate pump as well as the priority zone part which will shut down the other house zones. If anyone can clear this up for me i'll be very greatful. I plan on calling around again tomorrow in order to find a loasd calc person.

Thanks again.

[GradyWhite244]

Originally posted by jmoar5
Thanks for all the help. One small thing that i'm not getting at all. WHen you say i sould have the indirect tank on it's own circulator, does that mean that it needs a complutely separate circulation pump? I think that is what is being said. So i'm assuming i need a separate pump as well as the priority zone part which will shut down the other house zones. If anyone can clear this up for me i'll be very greatful. I plan on calling around again tomorrow in order to find a loasd calc person.

Thanks again.

Yes, the indirect tank needs to be on a zone by itself with it's own circulator. Do not use zone valves for an indirect due to the flow restriction they create.

At the top of this page there is a bullseye. Click on it & for about $50 you can download & run your own heat loss calculation. You even get tech support.

[Edited by GradyWhite244 on 03-13-2005 at 10:01 PM]

[ps]

The HVAC-Calc software is great, and Slant-Fin has a free load calc. CD, too. You can do your own calcs and compare to your contractor - chances are you do not need as much boiler as you have now.

Condensing boilers are great, but your location and application may require higher temps (if you have cast iron radiators, for instance), so then you go with a good, standard boiler with outside air reset and piping or low-limit to prevent condensing problems. Find the best installer you can and you should get a system that you are happy with. Continue to post questions here or heatinghelp's "The Wall" and you will get all the information you need to make an educated decision.