Heating Help

Subjectives and Objectives

@ May 19, 2011 12:51 PM in Convincing homeowner to switch?

From a purely energy-driven standpoint, heat is heat when comparing two systems delivered at the same overall efficiency and ability to adapt to changing loads (meaning modulation if done for one, is done for both).

A house with a heat loss of 50 MBH that is served by a modulating furnace and a modulating boiler will, thermally speaking, come out even. The parasitic losses of the furnace fan (say 1/4 HP or 200 Watts as your "delivery charge", is beat by a hydronic system with say, a P/S pump arrangement using, oh, 50 Watts each, or even less if ECM circulators.  But then you assume your radiation-side circulator runs all of the time when it is below a certain temperature outside. Your boiler circulator may or may not need to run all of the time.  So if you cycle your furnace fan off and on with a call for heat, you can break even on delivery (at the expense of some comfort).

With me here?

If there is a driving need for AC or filtration or humidification,
selling hydronics is a harder sell. The heating side, if the furnace is
top of the line in modulation of air flow and combustion and with good
duct distribution, will have a thin difference if any. A poor duct
distribution system seems to be the root of most air system discomfort.
Yes there are other factors, no question.

So, how would I make my case?

Comfort and the ability to more precisely deliver heat to a given space when I want it, where I want it, and not heat the rest of the house. OR, the ability if a single zone, to better adapt the temperature of the heating medium (be it air or water), to the load requirements at a given time. Air can do this as can water, but water gets the edge.

Are you selling radiant or baseboard? Now you are going to a different league. You lose the ability to compare appropriately.

If the air side is needed for AC, filtration or humidification, you can make the hybrid hydro-air case for possibly higher water efficiencies, ability to make HW and ability to branch out for more duct-coil zones. But then you no longer are comparing your father's air system.

So in summary, heat delivered to the same zoning at a given efficiency and appropriate distribution will have little difference to sell your clients in my opinion. Comfort and targeting the heat to more zones is the salable difference.

Happy Birthday, Johnny!

@ May 17, 2011 9:13 PM in Happy Birthday, Johnny White!

What do you get for a man who sets the standard and has so much fun doing what he loves?

I can wish no more for you than good health, good luck and continued happiness.

The Value of Infiltration

@ May 11, 2011 11:47 AM in Estimating Cost

Hold your hands about 18 inches apart, then move them back and forth between shoulder-width and describing the fish you wish you caught. That is about the range we are taking about here. (No, I am not being a "nickname for Richard" here, I am serious!)

Are you comparing say, an atmospheric boiler (huge gulps of air and excess air), or a power burner type, versus a mod-con with sealed combustion? That is why there can be such a range.  Also is the "from space" combustion air supplied by a ducted damper arrangement or are you relying on natural infiltration? Another wide range there.

If you are looking at "directly ducted combustion outside air to the boiler" versus "combustion air from natural infiltration into  the room", it gets easier.

If this is the case, here is how I would calculate this:

1) Find out from the manufacturer what their combustion air ratio is (draft fan cfm rating, basically). Also, while you are at it, find the modulation range, how far down it goes in RPM/CFM. 

You may have to make assumptions as to how many hours it operates at what speed and at what outdoor temperature of course. But for a ballpark number, I would take 70% of the full load number as a seasonal average and would include DHW generation. This is for modulation figuring, not hours of use.

Now make an assumption of how many hours per year the system runs. I would probably take any constant average number and cut it in half. This is "modeling on the fly", but all things being equal, different approaches will at least be proportional, right?

Say the manufacturer gives you a 150 cfm full capacity number. At 70%, that is 105 cfm. Typically, I multiply this cfm x 1.085 then by the design delta-T between the outside air and the basement where the boiler is located. Call it 70F, who knows.

So that 105 cfm at say 70 degree rise, I get 7,975 BTUH heat loss for an hour's operation on your coldest day.

From that number, I would apply the Heating Degree-Day (HDD) formula for your area. Say that is 6,000 HDD and the boiler runs at 90% From that and a 0.60 Cd factor, I get 304 therms of gas per year at the above figures if running all the time. But at 50% running time, this drops to about 152 therms. If you pay $1.80 per therm, that is $274 per year. When conducted into the boiler directly, this would represent what you might save.

Mitigating factors:
1) You are making an assumption that without ducted OA your home infiltration will otherwise be constant- Not necessarily so. When an open boiler fires, it starts the induction of outside air above what you would otherwise have naturally. Also, the open flue, even with a damper, draws air up the chimney all of the time. With direct vent or sealed combustion and the chimney gone, this loss disappears. This is your biggest benefit in one place.

2) If you have ducted dampers, unless the house is well air-sealed, this amplifies your basic infiltration, whether the boiler is firing or not.

Sorry to ramble, just some thoughts to get out. I hope they help.

Not sure I follow

@ May 10, 2011 9:55 PM in Boiler Signal

Each temperature circuit will require its own circulator and the lower temperature circuit its own mixing valve (as you stated). Given that boilers fire with wide differentials sometimes, I like to use mixing valves on all circuits, even if the high temperature circuit is approximate to the boiler temperature. Tighter control that way.

Each circuit can be constant circulation -with low Watt circulators of course- and control is by varying the temperature.

What I am not clear on is what flow the flow switch would respond to in your sequences. Maybe think about how you want the end result to be and work backwards from there? Could be my own lack of understanding your vision.

Space sensor and/or Outdoor Reset

@ May 10, 2011 6:24 PM in Boiler Signal

Many heating systems operate without any interior sensor. I had a Viessmann Vitodens 200 that ran entirely on an outdoor reset curve and constant circulation, with TRVs on the radiators. (Most, not all, I admit; not a candidate for pressure-responsive control.)
The system worked off the boiler controller and that included scheduled up times and sleep/away times. Without these, the system would run 24/7.

I both presume and hope that you would have ODR anyway for ideal comfort and energy savings.

The next step up is a room sensor which gives some feedback to the system (a question it never could ask itself before, "how am I doing?").

In my own house I have both, ODR and programmable thermostats. The circulators run constantly and the stats impose a heat demand, limited by what the ODR control dictates. Works very well. But without thermostats, just ODR with good curve control can work just fine.

The Wilo Stratos

@ May 10, 2011 3:40 PM in Pump continuously or cycle on / off

can accept an external analog signal. This is not their Stratos Eco but it is at the upper end of what I would call the residential line.

The Grunfos Alpha and Magna may also have this capability but I am not sure.

The Taco VS series of 00 circulators have been out for years now and also accept an externally generated analog signal. Make sure you select the correct application when you order, these are not interchangeable..

These  Taco VS series are not ECM motor circulators but PSC (permanent split capacitor) motors, so the cube-root savings of an ECM motor is not there, but it is more or less proportional to the load, not even a square root function but they do save energy. Given your relatively low electric rates (however impermanent they may be), the Taco VS series might make sense for you.

My first advice though is to have a good pump selection no matter what pump you use. Do not trade away what is an ideal pump selection for one with possible higher efficiency. Know your flow and head to as high a degree of certainty as you can, then find the best pump for that duty.

Dribs at the next level

@ May 10, 2011 2:00 PM in Domestic hot water storage efficiency

ecky, the logic scales-up to when you have a stronger draw and I should have made that clear and stated it. That five gallon bulge can allow about 2 minutes of shower time during which time your main source comes to the rescue. Your line recovery (a timed, occupancy-driven or manual twist switch recirculator!), would get that charged ahead of your shower to avoid a cold sandwich.  The tank is a tool to be used.

Tony

@ May 10, 2011 9:10 AM in Domestic hot water storage efficiency

I like your thinking!

Mikey

@ May 9, 2011 8:44 PM in Before and After- 1913 Gravity System Re-Pipe

Thank YOU for the nudge. Not my best work, it was done on the fly, but I all the more appreciate every one of you that does this for a living and tries to make a profit at it. This was a labor of love done in November. It always works out that way!

Thanks goes also to Lee Brooks and her family at EarthLee. If you are doing a project that demands something nice and specific, I suggest you treat yourself. Worth it and good value.

Putting the Mental into Experi Mental.

@ May 9, 2011 8:41 PM in Before and After- 1913 Gravity System Re-Pipe

Hey Paul- leave it to you, my friend. Thanks for the compliments and encouragement. My next boiler will be a Knight, but that is maybe a few years away at least. I want to keep going on air sealing and insulating what was missed over the years. Getting there!

My experimental nature left all kinds of ports and circulator-ready flanges I had kicking around. One may go to the side-stream filter, another to an on and off line buffer tank. (I have the tank.)  I insulated the basement walls in my shop (where the boiler is) so I no longer need heat down there so have yet another spare... I need a real hobby, no?

Hope you and yours are well, Paul!
Thanks

Brad

Sigmoid Freud and my Assembly

@ May 9, 2011 8:33 PM in Before and After- 1913 Gravity System Re-Pipe

Walked right into that one, Gregg! 
Good eye and good question. That piping was for thermal trapping recommended for the Taco iValves to reduce gravity ghost flow. The main CI zone circulator (the Wilo on the rack), runs constantly based on ODT so there is no real opportunity to test the theory.

The iValve rules that roost. When the other zones call (infrequently), this allows boiler water to be available for the main zone by default so nothing is wasted. The main house zone forms a nice baseline of heat for our schedule. Quite comfortable overall but still have to work on balance.

The downstairs is cool and I suspect the covers on the first floor coupled with missing orifice plates on the second, are contributory. Part of the next project!

The blue handled valve, that is a Macon balancing valve, half-inch, as a manual mixing bypass for what will be a radiant kitchen zone. All in progress. (Kitchen has only one piece of baseboard which was off of the cast iron zone so got bupkes for flow and heat. Now it is on its own zone. Overkill for sure!)

Thanks for checking in!

Missing the Vitodens

@ May 9, 2011 8:25 PM in Before and After- 1913 Gravity System Re-Pipe

Hi Robert!
You bet I miss it.  Still, I figured if I had this W-M boiler even at 82% I could make it better than the prior owner had it (with too much flow). By taming the boiler circuit and letting each zone play independently must have made a difference. The data is not in yet though and we only had a years worth of gas usage before we bought it. Work to do!

Bulge in the Pipe

@ May 9, 2011 4:48 PM in Domestic hot water storage efficiency

I agree with Gordy, storage losses or rather anything you save by say, adding insulation to an already well-insulated tank, is easily spent in one good shower.

The benefit I see to the 5 gallon tank (provided it is charged and ready), is so that you can wash your hands or rinse a glass without triggering larger generation sources. If this is in line to a large user (your main bathroom or kitchen), there is enough small use there so you can draw a trickle without penalty.

It really is a bulge in the pipe though.

"Should"

@ May 9, 2011 1:40 PM in Buderus G115: what does the word "necessary" mean in your opinion

in my opinion, is (obviously to most), a softer term and would have associated qualifiers. The qualifiers would be along the lines of, "Such and Such should be done to assure that (something something happens or does not happen".

Depending on the context and specifics, if a certain event was to be prevented (say condensation in the boiler to be avoided) and that did occur, then I would say you have some justification.

I have to step back on this because while this is my opinion, I do not know where you intend to go with this, nor what was specifically contracted, including results and performance. This would include adhering to "best practices", a very wide door sometimes.

In engineering and specific to best practices, there are as many ways to do one specific thing as there are engineers to stand around and point at stuff. Trust me.  In the end, what is justifiable is to demonstrate a return on investment or other means of energy savings which pays for additional costs to make those savings happen. That is the standard of care, at least to spell out such things so the decision is an informed one. From that point is where you get the different ways to get to the same result.

I think you have a plan!

@ May 9, 2011 10:07 AM in Heat Loss Calculation

With what you said, I agree, a Boiler Buddy as a LLH and buffer tank will take you over the humps. ECM pump, no question, but with TRV's or other "Back Pressure Devices" to impose a Delta-P response.

The 80-ish selection sounds good. The Lochinvar Knight WBN-081 (wall mount) or KBN-081 floor mount would be ideal in my opinion. Turndown will get you to 16 MBH input which is as low as I could find in this category.

The TT line is also good but you have a 60 (one of the first of the smallest!) and then the 110. So the 80 MBH range at least is an option for you. Play it well!

I have gone back and forth on wall vs. floor mount. Everyone loves the wall mount for floor space saving but in some cases there is no wall so that has to be built, at least a frame flat enough to install it. That adds cost to an installer and their price, so the floor model seems to work just fine. What gets me back to the wall mount is if you are in a flood-prone area. After last spring, I was glad we had a wall mount in the old house. (No flooding to speak of but some neighbors did not fare so well.)

"Necessary"

@ May 9, 2011 9:41 AM in Buderus G115: what does the word "necessary" mean in your opinion

is a term I write into my specifications for things about which one cannot do without. "Essential", "must", "shall", "required", also fall into the line of command language.

It is not "optional", nor "discretionary", nor left to others to interpret, in my opinion.

I cannot say what you should do with that, but I think it gives you some footing, if not moral or legal authority, to pursue remedies.

If you have no power

@ May 9, 2011 6:06 AM in keeps heating...

and you are still making heat, I would get in touch with Pope Benedict XVI (ratzi@pope.vat.roma) and your local media outlets in that order.

Seriously, how hot and have you positively disconnected the power? If it is running to limit, get a pro in there now.

That is all OK, actually.

@ May 9, 2011 5:58 AM in heat loss software

At least you know that your having the hotter water means you can handle the colder weather with ease. The good news is that you still have plenty of room to save energy and increase comfort. (You will love panel radiators, if you have not had them before you are in for a treat vs. fin-tube.)

What I would do, in short:

1) Put TRVs on all radiators. They probably come integral with them, with DiaNorm and others.  Each zone can "trim" to its internal loads (TV crowd adds heat, low winter sun adds heat, might as well not spend yours.)

2) Separate the boiler flow loop (kept at 180F to 140F minimum, usually)

3) Separate the radiation loop (kept at 180 maximum down to as low as will heat the house on a mild day.)
Given you have or will have panel radiators and fin-tube, we should assess the actual temperature needs of each circuit. Worst thing is that you will have the fin tube on its own mixing valve and ODR schedule and that is still a good thing, not a bad thing.

4) Bridge the boiler loop to the radiation loop with either an injection circulator, a 4-way or 3-way mixing valve to control the radiation loop temperature to an outdoor reset schedule. Set up the boiler with a similar control, albeit a narrower, higher temperature range plus a floating differential to reduce short-cycling.

With the above,  you should be able to reap nearly all of the comfort a mod-con will give you and wring the best efficiency from what is a good but not the top tier efficiency grade boiler.

As for size, yes, you see the dilemma! Just so many increments to go around. Maybe you can find a 75? (This is gas and not oil, right? I forgot if you mentioned, but at least with oil the firing rate can be changed within a reasonable range.)

To your last question-

@ May 8, 2011 10:04 PM in heat loss software

"Regarding the boiler, the 60BTU is too small. I would have to use the
90, the net on the 90 I believe is 68. Still oversized but???? What do
you think, would that one be ok? Gives me a little wiggle room anyway in
case I want to add more fintube."

I have not reviewed your heat loss calculations, but wanted to ask regarding your assumed boiler size and at what temperature the radiators were selected. This can have a huge impact on your efficiency and radiator sizing. "Stock" radiators are often selected at 180F entering water and sometimes 180F "average" water temperatures. This is a big difference in and of themselves, with the difference being 13% right there.

If a modulating condensing boiler, with 90 MBH output, the efficiency when putting out water over 140F, even to 180F, will be in the range of 85%. Once you get your supply water below 140 and return water below 120F. your efficiency will start to climb into the 90% range and up. With radiant systems having 75-80F return water, 95% efficiency is common.

I normally select my panel radiators for 140F water with a 130F average temperature. Lower than those temperatures, the radiators become too big and not as economical. But I will get condensing all the time of the year.  So please check your radiator selection assumptions, at what water temperature, specifically AVERAGE for consistent ratings.

Near Completion

@ May 8, 2011 1:55 PM in Before and After- 1913 Gravity System Re-Pipe

Well, the system is complete now, this is just where the photos were when taken. Not perfect I fully admit but satisfactory for our uses.  I particularly like using refrigerant grade fittings. The Master Bedroom suite in the attic also has an i-Valve.

The gravity zone which does the first and second floors, eventually will have TRV's installed on what are original Gurney radiators. Orifice plates were probably once installed because the first floor radiators get significantly less flow. TRV's on the second floor (which over-heats), will be the first step, this summer's project.

Part of my re-work involved re-supporting the big iron with clevis hangers, leaving room for insulation. Only the copper near-boiler piping was supporting that weight for the first 10 or so feet.

New expansion tanks were tucked up out of the way.

More Progress

@ May 8, 2011 1:47 PM in Before and After- 1913 Gravity System Re-Pipe

My final setup includes four zones plus provisions for future zones, part of my experimental nature. The core of this system is the gravity HW zone (40 MBH capacity), powered by a Wilo Stratos-Eco at a very low RPM. A Taco i-Valve performs ODR control on the zone and a Taco PC-700 works boiler ODR but to a narrow band. I only need 160F boiler water on the coldest day and my supply minimum is 140F to protect the boiler.

The boiler loop also has a Wilo Stratos-Eco, 8 gpm also at very low head. A Taco 4900 Pall Ring air separator is upstream.

In Progress

@ May 8, 2011 1:40 PM in Before and After- 1913 Gravity System Re-Pipe

I had the absolute delight to treat myself in both speaking with and doing business with Lee Brooks of EarthLee. I sent her a sketch and she and her family fabricated a stunning U-shaped P/S header exactly as I sketched it. I had a different vision when I started, of mounting this on a wall. But to save the additional expense of re-piping the DHW heater and a decision to use that wall space for my new shop, I elected to install the header on a Unistrut stand closer to the boiler.  My regret is that the EarthLee header is not more visible in the final installation!