small output boilers

Unknown

they don't sell instruments to test the flame quality , as far as I know . They do , however , sell the boiler as a package with a burner , circulator , control , relief valve , etc . All name brands . Without any of these things , you got no boiler to run .

My question is , other than the boiler being the biggest piece of the puzzle , why would you single out one brand , when they package the unit with many different company's products ? I agree with you , the installation of a boiler is not a DIY project for the vast majority of people .

jerry scharf_3

when are we going to see small output boilers???

I know that in the world of sales, bigger numbers are better. This is no excuse in my opinion for the modulating/condensing boiler manufacturers not producing lower output models. With more and more houses able to reach 10 BTUH/sqft demand level on design day, and 15 BTUH/sqft becoming common, we need lower output boilers! Not want, need.

If you combine the efficiencies of the boiler and emitter systems and the solid envelope design, the heat loss calcs are very low. Add to this the fact that I am seeing more and more that these calcs seem to run actual measured load (see Steve's post showing that 60% of design load was adequate 92% of the time.)

So it seems within reason to have houses with 20MBH design day load, and that half the time the load may be under 10MBH. Why are there not common offerings of boilers that go down to 10MBH modulation?

What is it going to take to get a 40MBH boiler with 4 or 5 to 1 modulation? Is it that the manufacturers don't see the demand? Is it that they see this as too small, and the cost per MBH looks bad? Is it just not part of "the culture" to want to build such a small boiler? Are there technical issues that prevent this from happening?

I can't be the only one tilting at this windmill. What do others have to say?

jerry

Brian Tober

Takagi?

Why not use a Takagi modulating heaters http://www.takagi.com/index.asp They are apparently suitable for space heating since they say so on the literature and have diagrams on the specs showing how to pipe them etc. Some on the site are saying they are not boilers and cannot be used for heating. I'm not sure, the codes are different everywhere. Then I heard that if its less than 200kBTU input they do not need to get ASME pressure vessel certified as a boiler anyway, so I still do not know the status of why you cannot use them for radiant heating in small apps. I am planning on using 3 TK Jr. models in a apt house that has old cast iron radiators and heat Loss clacs on each apt are less than 40K so a boiler would be way overkill and i'm of course trying to save energy for the tenants and make the place more desirable to rent.

Blue

these are disgraces of the industries. The same way they put circulators on the retun sides of the boilers for packaging and ease of storage. There is a lot to be said about all this. I do agree with your point, Jerry

Blue

hr

I agree, Jerry

then a lot of the "water heater" sources may disapper My wish list is 2500 BTU/hr to 25,000 for starters.

The small Vitoden ramps down to 25K. The 50K Munchkin gets down and dirty. Then again a pilot flame under a small well insulated condensing boiler would be LOW output

hot rod

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jerry scharf_3

You don't seem to understand the problem

Brian,

I feel like you made a decision and are looking to get people to say it's OK. It's not in my book, others told you that as well, but you don't seem to want to listen. You can build anything you want, but don't "offer advice" until you've done your homework, made the system work and have the design and numbers to show how it performs. IMO, you do a great disservice to the thousands of readers of this site who might think to follow your advice.

The primary reason you seem to have for choosing these is cost. While this is a consideration, it's not the only one and there will be other expenses in integrating this into a well designed heating system.

I'm trying to run a low output radiant system with constant circulation. The Munchkin T50 can run down to 16 MBH, but to get a constant running boiler, I need more like 5-10 MBH.

The smallest Takagi can only run down to 19 MBH, which is higher than the T50 I have. Beyond that, there are no condensing units available in the US. The one nice thing about the unit is that it has a 7:1 modulation range, while the small boilers have 5:1 modulation at best.

Then there is the whole issue of control. A boiler with outdoor/indoor reset varies the target water temp based on a load estimation, then modulates the burner to hold the that target. The tankless has a fixed temp and varies the burner with the flow. To get this to modulate in a heating application, I would have to vary to pump speed to get the right amount of water to inject into the primary loop to get the emitter supply temp I want. I could do this, but it's more work that getting a boiler designed for heating.

jerry

Bob Eh?

I have been contemplating this for some time and see several problems with low loss structure heating (and cooling).

First off I find most most loss/gain software just doesn't work well in the 10BTU/sqft ranges. I get over 100% sizing ranges! I suspect that is a result of not factoring low infiltration rates, HRV ventilation (Heaven forbid you use something like the Lifebreath/nutech Air Sentry to control it), High R factor envelopes, high end window and door systems (particuliarly with regard to orientation and shading), and low temp heating emitters..... and the CYA factor. Since I don't see a lot of information on exactly how each program factors ("Manual J compliant" eh?) these elements it does make it a crap shoot to pick a number. I am fairly certian that when you get down to these low requirement levels the only way to get rational numbers that permit you to design a system is to do full blown bin analysis with very detailed input on load inputs as the "slight" margins that creep in turn out to be a whole lot more significant for these low load structures. For instance, most programs figure the ventilation air conditioning is >= the base heat load at around 10BTU/sqft so there comes a point where if you had a zero heat loss/gain structure they would still say it takes 5BTU/sqft just so you can breath healthy... good HRV execution should be able to knock that down by >30%.

In my case I actually think I will use more energy making DHW than heating/cooling the structure on an annual basis!

Although we get at least a solid week where the outdoor temperature ranges from -25(Day) to -35 (night), in my case, I think that the observation that by far most of the heating requirement is conservatively less than 75% of the design situation.

Based upon this I think one needs to approach the heat and DHW with a single heat source. This will at least give you the potential to reduce short cycling with thermal buffering. It also means you really need something that can crank out at least 50Kbtu/hr to have reasonable DHW recovery rates. OTOH you likely want to get down to below 10Kbtu/hr for the lower end. That's only a 5 to 1 range! I suspect the problem is as the low end goes lower it gets really difficult to control the burner mixture accuratly for reasonable money, complexity, and/or reliability but hopefully they can get down to the 7 to 10Kbtu range (6 to 1) before the tradeoff point goes west. I also think that modulation range/low end cutoff becomes harder as the top end output number increases very quickly.

Don't forget that at these levels things like pump, fan, and motorized controls of any kind become highly relevant in the overall efficiency picture (Think TRV, Variable speed, ECM/ICM..... ).

Do we want to go into the following in this topic?

Why don't HRV/ERVs have ECM/ICM motors?

How about Hydronic Air handlers with ECM/ICM motors?

How do we factor in piping/standby losses as these hardly ever occur in the intended place. (My wife informs me that
she doesn't consider an indirect tank to be a feature in the living room..... Imagine ;-)) We really need decent tools to assess system insulation issues/impacts.... The Dead Men solution of just knocking a whole in the wall isn't going to cut it in this arena.

Is it just me that wonders why the industry in general isn't all over these issues as surely the guy who builds envelopes at this performance level should be a natural match to Hydronic systems and comprehend the operating cost benefit of addressing these issues? I imagine that eventually some of these issues will slowly come to the foreground as code standards force it but I don't expect that will occur in a relevant time frame.

It could be worse..... Manufacurers of water to water heat pumps suitable for ground source applications seem to think 2 Ton single speed is the low end of the spectrum answer (interestingly some actually use ECM fans in units packaged as part of air handlers....)!

Maybe a worthwhile goal of this discussion should be assembling a directory of resources that address these issues.....

Brian Tober

I am considering them based on saving money on gas bills. I had no idea about them until recently, and was going to put in 3 small slant-fin boilers, the smallest one they make is 60K BTU. I only need 36K max on the biggest apt. according to Slant fin HE2 software so why would I want to put in 3 60K boilers at $998 cost at Home Depot each? Like I said I am doing my homework to see if they will work, and if code allows them. If they will work, and cost 600 each, and run much more efficiently, then I solved my problem. It seems like the heating pros are anti-tankless on here why is that?

Brian Tober

Actually Slant fin makes a 34K BTU input but its just under the heat loss calcs I have so I would have to jump to the 60K boiler is what I meant. What other options do I have in a small application other than the tankless stuff. I am on here to learn about my options. Thanks

hr

Most heatloss calcs

have a fudge factor. I think I would risk a 34 K boiler for a 36K load. Keep in mind how many design or below days you see in your area.

Keep in mind, of course, that you need to look at the boiler OUTPUT figure when sizing.

I think the issue with tankless, from a heating contractors perspective, is the lack of code approval, and sometimes issues with insurance carriers that inspect for listings.

Tankless heaters are wonderful when used for what they were designed for, DHW production! IF the tankless manufactures are serious about the heating market, get them listed for such an appliction.

Send them out with 30 psi reliefs.

Send them out with the correct pump requirement.

Warranty that HX for 15 years or more like most boilers do.

Be honest about the BTU output when used in a pumped hydronic application. If it presents 50 feet of head to supply 100,000 BTU... that's not going to cut it with any heating pro

You can usually find the correct tool or equipment to get the job done efficiently and safely.

hot rod

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Steamhead

Hot Rod nailed it, Brian

When looking at residential boiler ratings you will see three numbers: "Input" in BTU (on gas boilers) or "Firing Rate" usually Gallons per Hour but sometimes in BTU (on oil) tells you how much heat the burner is generating. To convert oil rates in Gallons per Hour to BTU, multiply GPH by 140,000.

The second is "DOE Heating Capacity" which tells you how much heat the boiler will deliver to the system piping.

The third, and the one you want, is "Net" or "IBR" or "IBR Net" depending on how they worded it. This tells you how much heat is available at the radiation by adding an arbitrary "piping and pick-up" factor. This figure should be close to the design heat loss for best efficiency. A boiler too big will short-cycle, never reaching steady state. A boiler that's too small won't heat the building at design conditions, i.e. at the lowest outdoor temp specified in the heat-loss calc.

On bigger jobs, installing several smaller boilers gives us the ability to match the heat input to the building's heat loss by operating one or more boilers as needed. But the small sizes of your apartments precludes this option.

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Brian Tober

Yes I understand the Output is what I need to look at, but most boilers model numbers are based on the Input figures. Such as Slant fins S-34 model is 34K AGA Input with IBR of 25K which is a bit too small for my Apts, so I have to jump up to Model S-60 with 60K AGA input and IBR of 44K for all 3 apartments which is oversized a bit. I was considering the tankless stuff but sounds like most on this site don't endorse this approach since they are not true boilers with full code approvals. Thanks for the advice everyone has given its very interesting and valuable service this site is providing!

S Ebels

Brian

Check my post to you on the "want to use a Munchkin" thread.
Maybe it will help you to understand some of the difficulty in adapting one of these to heating use.

leo g_13

Just got burned

on one of my jobs. The heatloss matched the output almost to the BTU. Unfortunately, the "dreaded" design changes happened. Different windows (and more of them), outside walls moved further out after final inspection, and different flooring choices. So sometime this summer, it's hi-ho, hi-ho, its off to a boiler replacement I go!

The more I think about this situation, the more I start to feel that oversizing the boiler a bit nowadays is not quite as bad as in the old days. With the tekmar and like controls, the boiler is not going to short cycle as much, as these "smart" controls learn the boiler patterns. And the other biggee that seems to be happening more and more now, is that it is not only the master bath that is oversized. A lot of homes now are putting baths off of every bedroom, and oversizing the tubs for the guest suite too!

Leo G

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Brian Tober

PLC control?

Jerry are you familiar with PLC controllers? They can be programmed to do all kinds of control functions. Problem is you have to learn the software and play around with the logic until you get it working the way you want it. They are used in industrial control applications but can be used for anything you can dream up. There is a company that has basic PLC's for around $99 and up www.automationdirect.com Maybe your situation will require a custom written control strategy that you can invent yourself using the DL05 PLC.

Constantin

Hmmmm....

It is certainly true that finding a low output boiler is difficult, if not impossible, in the USA. In other areas of the world where climates are milder, houses tighter, such boilers can be found. For example, I'd love to see a boiler that is as easy to install and hide as a average kitchen appliance - as some in the EU allegedly are.

Controlling flame quality at very low output levels may be a challenge, as even minute "burps" on the intake side of either the gas or the air side could cause severe flame/combustion issues. At some point, it may simply make more sense to have external buffer tanks that can pick up the slack between firings...

Constantin

Is the heat loss the problem?

It's pretty hard to deal with scope creep... whether you're a consultant, heating contractor, etc., the worst thing that can happen to you is a client who keeps moving the goalposts.

One thing that is making life a lot easier for contractors though is the emergence of extreme modulation ranges in heating appliances. For example, the NTI Trinity 400 advertises a input range of 400kBTU-25kBTU for a modulation range of 16:1. Such extreme modulation capabilities allegedly allow the NTI 400 to handle large dump loads such as jacuzzies and the like while also allowing fairly reasonable heating control.

I wonder what valve is in the NTI 400 and whether the technology can be adapted for lower-input boilers. I'll bet one ice cream that a 16:1, 160kBTU max input condensing boiler would be suitable for something like 90+% of residential installs where hot water (not steam) is the heat transfger medium... Imagine how much as a supplier you could minimize the scope of your product line while maximizing the scale...

Constantin

I totally agree...

I have used HVAC-Calc to determine the anticipated loads for my home. Since the version 7 Manual-J that the author apparently used as a basis for his calculations did not include provisions for HRVs, no such options exist in HVAC-Calc, as far as I know.

On the other hand, I hear good thing about Manual-J, 8th edition. This edition apprently makes much broader use of environmental factors and starts to back off from the 25% built-in fudge factor that previous editions apparently included. Furthermore, there are so many environmental factors beyond the purview of the contractor that getting an accurate heat loss calculated up front is a bit of a crap shoot.

If a home is already standing, a blower door test plus past home bills are probably the best indication for what the heating load ought to be. The real magic in heat loss/gain programs is when they can tell you what the gain/loss ought to be before the home is built.

Furthermore, ECM-like motors seem to be already in use in HRVs. For example, the Lifebreath TRV 195 and 300 I have installed in my home come in 5 speeds. It is unlikely that they're achieving these speed differentials via winding 5 different kinds of pole sections... PWM or other forms of DC-motor control are far more likely candidates, particularly if you go with brushless DC motors.

If it works in a washing machine, it'll work in a HRV too... take a couple apart and you'll see what I mean. Some have ECM motors, some don't. More I cannot say.

Anyway, ECM motors certainly have their place - they make for a compact solution that allows constant air flow speeds in AC systems, whether some or all registers/zones are open. However, for something as simple as a HRV, a simple DC motor might be far more appropriate.

jerry scharf_3

Brian,

I do know a thing or two about control systems. I've built a number from the ground up, and am in the process of doing one for a demonstration project. I have a fair background in control theory, and some practical application time at NASA Ames.

PLCs usually program by relay ladder simulators. PID controllers use fixed analog input to output functions with three components (proportional, integral, differential.) In the classic sense, they are 1 input and one output, though the design has been extended to cover multiple inputs.

Then there are things like fuzzy logic and neural network controls, which are more subtle but can considerable advantages in certain applications.

Now comes the pain. In a true control system, you would control the combustion through emitter, with all safeties and feedback. When you buy a boiler or water heater, it has already done a bunch of control work, and you have to dance with what you get from them. I opted not to get a certain vendor's boiler because it wanted to too mcuh for me, and that would have made my job for designing controls much harder. When I spoke with them, they completely understood where I was coming from.

It's one thing to toss out some parts and some acronyms, it's quite another to build a system that has excellent efficiency and comfort. This thread is aimed directly at that goal.

jerry

jerry scharf_3

> I am considering them based on saving money on

> gas bills. I had no idea about them until

> recently, and was going to put in 3 small

> slant-fin boilers, the smallest one they make is

> 60K BTU. I only need 36K max on the biggest apt.

> according to Slant fin HE2 software so why would

> I want to put in 3 60K boilers at $998 cost at

> Home Depot each?

Yet you protest this is not about the boiler costs. Condensing, modulating gas boilers cost several times as much, yet many of the people here install them regularly. Read on and see why.

> Like I said I am doing my

> homework to see if they will work, and if code

> allows them. If they will work, and cost 600

> each, and run much more efficiently, then I

> solved my problem. It seems like the heating pros

> are anti-tankless on here why is that?



I don' think a tankless makes a good closed loop hydronic heating unit. The better boilers out there cost much more, even at the wholesale price. What's the difference?

They are designed for closed loop heating applications. It means that heat exchanger flow is an important deal, much more that tankless units. Also, since there are less external issues (scale, oxygen laden water,) the heat exchangers in boilers are designed for much longer life.

The controls built in boilers are designed for heating. The tankless units drop flow when they can't reach temperature goal, someting that makes no sense for heating. The better boiler controls also use things like outdoor/indoor reset to adjust target temperature to provide longer burns and more comfortable systems.

Tankless units are not designed to burn continuously. With modulating boilers and continuous flow emitter designs, it is possible for the unit to run continuously for months. Will the tankless work? yes. Will it last? who knows? With the manufacturer stand behind you if there are any problems? probably not.

The "heating pros" here put their reputation on the line with every job. Every call back costs them money. Every call back tarnishes their job in the eyes of the customer. Since there are many other parts and a great deal of labor involved with a complete system, it seems like a false econony to use something not designed for a job. Also, since the overall job costs are high from the customer's point of view, who wants to show the customer the cheapest piece of equipment not even rated for heating. IMO, the customer would be right to be very upset. If the heat goes out in the middle of winter, the customer is going to be very upset, and that "cheap" heating unit would be a lightning rod whether it was the problem or not.

Now for the crux of it: HAVE YOU EVER INSTALLED A HEATING SYSTEM FROM SCRATCH? It sure doesn't sound like it. You've "just discovered" the Takagi units, and certainly have never installed them in a functioning system. You protest that it's not about price, but all you do is talk about the cost of the unit at Home Depot. Some people might be upset about the Home Depot part, but I don't care. I'm annoyed because you seem to have almost no direct experiece in this field, yet present your beliefs in a way that others might be foolish enough to listen to.

jerry

Constantin

State/Space.... here I come.

Remember some of that, way back when I was still transforming/multiplying 8x8 matrices (or whatever it was) by hand to resolve just where a robot arm ought to be given a number of inputs (i.e. open loop control).

I would like to think that the combination of Simulink and National Instruments should be able to put a capable toolkit at your hands. On the other hand, this route has a steep learning curve and an even steeper price tag.

Bob Eh?

I was quite surprised that the Lifebreaths used PSC (Page 5 in your manual) Given the benefit of constant airfow and low power it seemed like a "poster" ECM application to me.... I do agree that brushless DC is another possibility.

So far I find if you pick up the phone and talk to most air handler/HRV/ERV companies they don't seem to get it when out point out the desirabilty of low power consumption

You will be greeted with stunned silence when you point out that their crappy fan motor is increasing your cooling load by 15%! Then point out that it also doesn't maintain enough flow because you want decent filtering and to use Hi Velocity distribution to promote good air mixing because the motor won't drive reasonable flow into 1.5"WC Mind you some will suggest going up to a 1HP fan assembly!

You have message further down about burner modulation... notice that the entire NTI line cuts off at ~ 25KBTU at the low end. and varies the modulation from about 4:1 to 16:1 from there. Your observations about the sources of instability becoming an issue at the low end points out tome that the engineering needs to concentrate on conditioning the airflow and gas flow characteristics before the burner to overcome those points. Aerodynamics as opposed to thermodynamics I guess.....

Manual J8 is an improvement.... Lets see, at three years per cycle and the current incremental improvement rate.... the standard might catch up to todays requirements around about 2015!

Now here's something that would provide a huge payback on our tax dollars if that gap got closed faster.... The labs certianly have most of the science needed to get us there as we type. Given our fat energy use we need tools that are a lot better to do the front end design reliably to attack the problem with.

bob_44

Jerry

I thought PID was proportional,integral,derivative? bob

Constantin

... never thought of that!

... this is similar to the issue of how to deal with pumps that have far more flow capability than is needed. Sooner or later, you'll start heating you home with electric resistance heat via the pump! FWIW, I hope that the ΔP pumps from Grundfos, Wilo, etc. make it into wide distribution here ASAP, because they have the potential to simplify heat emitting systems in similar ways to how modulating boilers simplify seizing boilers properly (i.e. they give you leeway).

I had no idea that the fans inside the TRV/HRV/ERV were that wasteful. I always thought that PSC were relatively efficient electric motors, as motors go. Hmmm, something else to investigate. As for the reason ECMs are not more widely used, it may also have to do with the value-pricing that GE, Emerson, etc. enjoy on these units.

As for manual-J and paybacks, the crux is not in the standard (which is a good start) but in the application of what we already have. Until the industry is required to do a Manual-J-compliant heat loss calculation and to size accordingly, then Manual-J is only relevant to the ethical installers that use it.

Never mind the huge potential energy savings that a proper nation-wide energy standard in home construction could entail. It's simple enough to build homes to have less than 5BTU/(ft² x DD) heat gain and loss, so why not start down that path... well, actually, let's not because Dan likes his peace in the valley and this thread may suffer the same fate as the energy policy threads.

Brian_34

Thinking

Jerry,
I graduated from Monmouth county vocational school with honors in HVAC (high school part time program), and also graduated honors from DeVry in electronics technology. I worked for several HVAC companies then moved into controls field and have been away from HVAC for several years. A lot has changed in the industry since 1986.

A lot has changed in the controls industry too, and every industry, especially automotive.

There are serveral ways to program plcs other than ladder logic, the newest and easiest is Entivity's WinPLC that uses flowcharts and Microsoft Visio so you can connect pre built function blocks.

I know this is getting outside the scope of the thread but the more diverse the discussion, the more people can learn, and make thier own decisions based on various viewpoints. In college they called it "critical thinking".

jerry scharf_3

I was going to post sooner

PSC motors aren't great. ECM motors are much more efficient. The Sterling/Ultimate Air ERVs use a pair of ECM motors in their ERV. Because the media exchange part is so efficient, they needed to improve the fan motors to keep their efficiency numbers above 90%.

jerry

Al_11

SlantFin boilers

Did I read correctly that Home Depot is now selling slant fin boilers? Does the homeowner get a pamplet covering years of trade school and years in the trade, I am assuming no more then 15 pages to deal with the short attention span when it comes to little details like load calc, piping, and safety.
any thoughts on this
AL

Jason_15

HD selling boilers

Wow!! I wasn't aware they were selling boilers. Is this legal in some or all states? Maybe you should make this it's own thread, I'm sure many people will want to comment on this! Just imagine how this will make insurance companies cringe having average joe putting his own boiler in. Not good.

Joe Brix

On Long Island

They've had the basic nat draft oil and gas models on display for years now. That's why I won't buy their stuff.

Brian_34

Home Depot and Lowes sell boilers

Both big box stores sell boilers, Home Depot sells slant-fin and has a little form to fill out with room sizes etc. to fax off for them to size it for you (its done in NJ by Palermo supply co.) Lowes sells Hydrotherm Saber boilers which have stainless sheet metal jackets and are a little bit more than HD slant-fins. Not sure who helps you size it.
As far as installation, think about this, you don't have to be ASE certified to buy critical automotive suspension, driveline, and brake parts! I doubt the avg homeoner is gonna try to put his own boiler in, they are targeting the tradesmen, and offer installation services too.

Weezbo

*~/:)... Heres a thought....I have seen small output boilers...

meggars with so much soot, condensation etc etc inside of them that it was a wonder they could support combustion..At All.....
I realize that isnt quite what you were refering too at the time,just thought i'd roll it by you....
It gets fairly cool around this neck of the woods yet there are indeed homes that have low heat losses....many of us would like to check in on some lower input modulating burners..especially in Oil...To be honest i was very interested in the Herrmann boiler and what s what with it....
Along time ago far far away i had the bright idea to try my hand at making the oil burners worky at lower end... why that shouldnt be done other than in a computer generated reality is obvious to me. There are far too many minor technicalities to deal with than one would likely have at thier focal point when embarking on "Mr. Bills Dynamic home tested oilfired high fuel pressure boiler" capeable of premature explosions and Very loud ear rinnging Bangs...:)
I would like to see some oil burners that were designed in the 38K top end,that were lashed to a boiler that could support stepped modulation and condensing....
I intend to make it to see Chuck Shaw in Anchorage on the 6th as he has come all this way i hope to get some info to disseminate among some friends on the vision controls...While there i am (saying this with the fingers and i's crossed) going to find my buddy J.D. and see if i can get him to give me some straight scoop on the monitor oil fired ....He has been selling them now for a while...this is a pinner boiler and cha...it just might be holding its own in Anchorage ,...and hey its only a luu bit chillier around here*~/:)
OK

Stay Focused,...A thousand points of light ....stay the course...a thousand points of light..... more caffine ...:)

Mike T., Swampeast MO

We'll See Them When AND IF There is Sufficient Demand

Just think about it.

Despite their advantages hydronic heating systems have a small and dwindling market share in this country. Couple that with a partly understandable reluctance to change in the trade and there just isn't much demand.

While modulating boilers [seem] to work best when sized as small as possible, some tend to see the modulation as a way to oversize without the "old" problems. It wouldn't surprise me if some replacements using a modulating boiler are made with even larger output than the already oversized unit it's replacing! After all--NOBODY wants a "not enough heat" call!

These boilers aren't coming from the U.S. where boiler manufacturers have little or no money available for R&D. At a minimum the guts come from Europe where the technology is almost mature.

The cost is comparatively high to begin with and much of that cost comes from controls and expensive manufacturing techniques. A smaller unit will seem even more expensive. Such is DEATH in the American marketplace with "bigger" (in some sense of the term) is almost always considered better.

The Europeans have their stereotypes of us just as we have of them. We often consider their heating "cave-like" while they consider ours "sauna-like". We often consider them homes cramped and tiny while they consider ours relative mansions.

-----------------------------------------------------------

If you want smaller boilers:

1) QUIT OVERSIZING!!!!!!!!!

2) Politely pester distributors and manufacturers.

Bob Forand

When they target tradesmen they aproach them the same way they approach manufacturers. THEY DICTATE rates and pricing. Big Box is BAD for the trade PERIOD !!!

larry

With regard to hydronic air handlers not using ECM motors...

When I went shopping for such an air handler, I felt very frustrated that they pretty much don't exist from any vendor. The only one I know of is a Lifebreath model that has an ECM option. However, other than the 6 - 8% efficiency improvement of ECM over a speed controlled PSC at similar fan speeds, Lifebreath wasn't taking advantage of the technology to justify the much higher cost.

It seems the main issue is finding a speed controlled hydronic air handler that has control logic in tune with taking advantage of hydronics and modulating boilers. By this I mean the lowest air speed delivery in conjunction with weather responsive modulating boiler temperatures to meet building losses with the air handler running "constant circulation". ECM may just be a better way to implement this type of setup, but it isn't absolutely required. The primary electrical savings of ECM seem to come from the fan laws which say that the power reqired to run a motor at a lower speed drop by the cube of the speed change. So for example, a fan at full speed of 1000 CFM using 800 watts would only require 100 watts if run at 500 CFM. If you can reliably speed control a PSC motor, you get the same savings (minus 6 - 8% for the base technology being less efficient).

I ended up getting a hydronic air handler from Ecologix which has worked out great. They speed control an appropriately speced PSC motor. With thermal sensors for heating and cooling their control logic tries to run the air handler as slowly as possible. Just like an ECM, the Ecologix ramps up to speed so you don't get that big bang. At outdoor design temperature (0F), I was still operating such that the boiler was still within condensing range. I did notice looking at their control board that two output terminals are labeled "ECM". These aren't currently used, but it must indicate some of their future plans.

Unknown

They also have the oil fired model

as well as Taco circulators , controls , valves , Beckett burners and parts , Lux and Honeywell thermostats , Honeywell controls , some Watts products I believe , as well as many brand name fittings and pipe . Do you boycott all these brands also ?

Joe Brix

Burners and boilers

are not DIY projects. If a homeowner wants to take a wack at a thermostat or replace a circ. fine. But you need instruments to set up a burner. Does yor avg HD customer have these?

Ron Schroeder

It's not the boiler, it's the burner

It's more of a burner issue than a boiler issue. It's next to impossable to find even a .5gph nozzle let alone anything smaller.

I am presently trying a .30gph nozzle from Hago on a Riello burner in a Buderus G115-3 boiler. So far no combustion problems.

I personally think a 2 stage burner with about 4:1 ratio between high fire and low fire, like .60/.15gph or .8/.2gph would be ideal for retrofit.

norfitz

An installer who works for a \"thrifty\" mechanical

contractor told me that Takagi tankless water heaters have magnetic flow sensors, and that when he was ordered to install one into a hydronic system which had ferrous piping and radiators, he was called back to find the magnetic flow sensor not functional because it was bristling with metallic particles. I'm not aware how many other tankless manufacturers use this method to read flow.