BTUH Load From Existing Radiation

So I am trying to figure boiler sizing using the existing radiation I have available. What is a typical water temp @ radiator to calculate BTU radiation? I was thinking 150-170* is a safe number? This is ball park what I have available in my 1500sf rancher. Living floor 2 zones single loop, has ~125' of baseray CI baseboard total. Basement has 1 zone single loop with (03) 12 section 32" rads that I never use but want to include in my numbers.

Here is what I am calculating using 170* temp @2,000Lb/hr
CI Base 125*450=56,250
Rads 1005/ea*3=3,015
+DHW= 30,000

Net BTU/H= 89,265

Does that sound about right?

With that said, what type of headroom should I leave above my calculate BTU/H load? 15%

I would have a heat loss calculation done on your home before you
go any further.

Generally the issue of boilers comes down the fact that many boilers
are oversized for a heating system and the radiation is also larger than
needed in many cases but not all of them.

I recommend to many folks that they invest in two paper back books written by
Dan Holohan The first being "Pumping Away" and the second being "Classic Hydronics".

Dan writes for the Layperson and the Plumber alike and makes the reading fun and easy to understand and he provides you with his lifetime of plumbing experience with the work he has done in heating and cooling as a plumbing troubleshooter and and technical sales representative for B+G and others before he began working for himself and writing his books.

Mr. Holohans books are available from http://www.dansbooks.com , Barnes and Noble or Amazon.

Thank you. I was looking at getting that book I have heard a lot of good things about it.

I do believe I have too much radiation for my space, but like you said a HLC is in order for sure. Am I off base thinking that I would need to size the boiler to the existing radiation though? Regardless of what the heat loss calcs say, I am still limited to the potential available radiation. Only variable would be boiler high temp for heat circulation to determine max BTU/H potential, right?

I want to help you. Please invest in the two books I mentioned and you can do just about everything except the business with the blower fan in the door to pressurise a home to check for leaks with a smoke generator or heat leak detector with what Dan tells you in his books.

In his writing he goes into detail about arguing with plumbers about doing heat loss studies and how they complain that it takes to long to do and they will size the boiler by the previous boilers size and or by counting the total length of the baseboard to figure out what they should install which is more than what is typically needed.

In my case with my leaky old school house, I have backed my water temperature off to the point where the boiler is running on 120 low 150 high with a ten degree differential. The KAA-4-1 is running very well and not running that much with coal or oil simply because I added a layer of high temperature(1000 degree fiberglass insulation) furnace insulation to the steam chest and I cannot believe how much heat I am making with so little rice coal per hour.

1. Heat loss study.
2. Dan's books.
3. Then dive into what you want to do and then decide what is more cost effective adding insulation and or new windows or a very small stoker boiler.
4. look some more at what you want to do.
5. examine the expense and the return on your potential investment and then decide what will give the quickest return on your investment. In most cases the repairs are the least costly option for upgrading a homes heating system with insulation.

FYI Dan also explains to the reader how the hot water temperatures used in Europe are lower than what we use here as their heating regulations are more strict in Europe and the homes are much more energy efficient.

Ok, to the drawing board.

Thank you.

Does the radiation heat your house adequately?

Rob R. wrote:Does the radiation heat your house adequately?

Honestly I don't know. I have not really used it that much. When I moved in 2years ago I installed a coal stove in the basement, MKIII. That heats my entire house all winter on about 3-4tn. I run the boiler for DHW and for heat during the shoulder months. April & October. When I do use the oil boiler, it keeps my house comfortable.

As far as the heat loss calcs are concerned I did a few cursory calcs using what I could find on line and I get ranges from 45k to 68k.

Im in no rush to change what I have, merely curious and would consider replacing oil boiler for coal boiler next year.

The heat loss could very well be what you calculated. It was common to oversize radiation, and the house may have had improvements over the years that reduce the heat load.

Since you are unsure how well matched the radiation is to the actual heat loss, I think it would be worth the time to download a free copy of Hydronic Explorer and run the numbers.

So I ran the numbers though the slant fin app. (Nice little program)
Im not sure what to think. Either these calcs are not accurate or the current boiler and available radiation is WAY overkill. Im going to sift through the numbers again to double check my work.

Ahh, What does your MkIII coal output rating and 3-4 tons per season tell you? after all there is a proven track record there.
Might can work backwards from there???

Is Quakertown really a 12*F winter 100 year low temp? Or will the oil boiler remain to make up the worst case low temp?

McGiever wrote:Ahh, What does your MkIII coal output rating and 3-4 tons per season tell you? after all there is a proven track record there.
Might can work backwards from there???

Is Quakertown really a 12*F winter 100 year low temp? Or will the oil boiler remain to make up the worst case low temp?

That's exactly what I was thinking about my existing stove and BTU output.

The 12* temp was based on the slantfin numbers they provided. They are basing their numbers off the Hydronic Institute H21Manual. I am going to run it using 0 to see what it does to the numbers.

Link to the manual. Figures are on the last two pages. https://www.google.com/url?sa=t&source=web&rct=j&url=http:// ... np0XAGuKHw

All but the smallest of coal boilers would probably do a fine job in your home. As McGiever pointed out, your previous coal consumption tells the story...3-4 tons is not much. I don't have time to do it now, but if you want to spend the time to look up the degree days for your area, you can come up with a heat load pretty easily.

If you want some good entertainment you can read some of our past threads on boiler sizing.

Scottscoaled Boiler Sizing Method
Coal Boiler Size
Keystoker KA-4 or LL Wl110 ?? Buying Friday
Coal Boilers WL-110 Vs KA-6 Vs EFM520 Vs VF-3000
Which Coal Boiler to Get

Good post: Keystoker KA-6

4 tons for 180 days at 75% efficiency is roughly 17,500 BTU per hour. According to Larry's 2.5 rule, your appliance should be able to output 2.5 times that much for the coldest days.

17,500 x 2.5 = around 45,000 BTU per hour

Looks to me like you don't need anything real big to heat that house...

If you ran the hand fed less than 180 days just tweak the equation to fit. A ton of coal is roughly 25 million btu's. 75% is a safe efficiency number.

4 tons in 150 days is about 21,000 BTU's per hour, then x 2.5 = around 52,500 per hour for the coldest days.

Another semi related possibility is with not moving on this boiler addition until maybe next season you may be able to take advantage of a newcomer to the stoker boiler arena...there is mention of DS Machine bring a newly designed stoker boiler to the market in the not too distant future...prototypes are being or will be tested soon to get some real life field testing in.
May be worth keeping an eye out for this new entry.

Deals like this are what I would watch for: **Broken Link(s) Removed**

I can't believe no one has grabbed that one.

Qtown1835 wrote:Living floor 2 zones single loop, has ~125' of baseray CI baseboard total.

That Baseray radiation is a wonderful product. It provides radiant heat, and is not disruptive to furniture placement like free standing cast iron radiators.