Minitherm, Solutions or Raypak Residential

hr

you need a bigger pump!" That's a common Tech Support response when you have copper tube problems.

Ironically, more often than not, it is the correct response :)

As Bill mentioned flow is paramount. PS should be mandatory as it is on the condensors on the market. Most condensors show only PS piping in their manuals. Too bad early copper tube manuals didn't stress this. It wasn't until Holohan wrote that great PS guide for Teledyne, did we even see much mention of PS, at the residential level.

Years ago CT boilers had thermostatically controlled modulating gas valves on even the smallest models. This was a huge plus when these boilers are multi, micro zoned. It was a fairly expensive gas valve and maybe got value engineered out? Sounds like two stage firing is making a comeback.

PROPERLY applied is the key phrase here :) Knowing what and how "proper" is the challange.

hot rod

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Back-Burner

Laars Minitherm, Lochinvar Solution or Raypak Residentials

I've narrowed my selection to theses gas-fired boilers. All have 2-stage firings. All my zones are baseboard (2 zones plus indirect dhw). Need to know if there are any quality / reliability / installation issues and is there one that is head and shoulders above the others in quality etc. Thank you.

bigugh_4

Which one ?

It could be a matter of the OEM parts installed on the boiler. I.e. B&G,Taco, Honeywell, or other national brands. Which brand is locally and readily avaliable. It is tough to have to find somehting that'll make the boiler work if OEM parts are not at your finger tips. As for the boilers thenselves It is up for grabs which is best. All three have served me well. You might look at technical (local ) reps also. It is nice to have local intrested help when on the cold night the boiler takes a holiday!
JMHO
bigugh

hr

My

choice would be Lochinvar they seem to have the best quality.

I was very unimpressed with a Raypak I installed a few years back. All the screws were stripped, the bypass was leaking and not inserted and soldered properly. Just looked like a rush job on the assembly line.

hot rod

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Boilerpro_3

Sort of funny, I've had the opposite experience

> choice would be Lochinvar they seem to have the

> best quality.

>

> I was very unimpressed with a

> Raypak I installed a few years back. All the

> screws were stripped, the bypass was leaking and

> not inserted and soldered properly. Just looked

> like a rush job on the assembly line.

>

> hot

> rod

>

> _A

> HREF="http://www.heatinghelp.com/getListed.cfm?id=

> 144&Step=30"_To Learn More About This

> Professional, Click Here to Visit Their Ad in

> "Find A Professional"_/A_

Boilerpro_3

Sort of funny, I've had the opposite experience

I installed Lochinvar for a while, but there were a mix of what appeared to be design problems (Burnt thermocouples, pilot outages) , and horrible factory support. Also, basic controls like pump off delay to prevent boiling in the tubes during shut down are not standard and very small tube passages creating the need for high head pumps (read more expensive and higher electrical usage. I have not installed a Raypack, but service one and the design appears to be much better than the older Lochinvar. Pump off delay, most come shipped with a 5 to 1 modulating gas valve, and very nice tapered burners for stable flame at low modulation. I've seen many that have not been touched for 20 to 30 years in domestic water heating surface with water hardness above 20 Grains. I am looking at Raypack closely once again and have found my loacal reps to be exceptionally knowledgeable.

Boilerpro

bill clinton_3

boilers

My experience with Lochinvar and Raypak has been limited, but my general impression is that the makers attempt to pack in more quality than does Teledyne-Laars. They do seem to be a bit more difficult to work on than the Laars.

That said; I do have lots of experience with the Td-Laars. Probably around a hundred of them. They're easy to work on and quite reliable if you take care of a few things:

1. Limit the time they run low temperatures returns. Condensation will always form on the heat exchanger on every cold start. A small amount of soot forms every time that burner lights off and shuts down. If the hx is wet, that soot will stick and accumulate until draft is pretty near eliminated. They are blessedly easy to clean, but on high mass, low temp radiant systems, you could be doing it every two weeks.

My way of dealing with it is to run primary-secondary pumping (even if there is only one zone)and use one of those thermostatic valves that prevents ciculation in the secondary loop until the primary loop is up to 140*. You could do the same thing with electrical controls if you wanted.

2. The other issue is flow rate. Low mass boilers don't much like low flow: runs the delta t across the heat exchanger way up causing thermal stresses. On the TD Laars, the high limit aquastat is not well placed and, under low flow conditions can allow superheating before it shuts down the burner.

The cure is the same as for low temperatures: primary-secondary pumping.

3. Prevent no-flow firing. If the pumps or controls should fail, that poor positioning of the high limit probe will allow superheating in the heat exchanger. In fact, I have twice seen scenarios when the circulator failed and thermosyphon flow ran backwards, keeping that aquastat probe cool. This was on radiant systems with polybutylene tube. Created a lot of grey goo and a very wet floor.

The cure is a flow switch that prevents burner firing until flow is established.

With these items taken care of, the TD Laars is reliable, efficient, and long lived. I have installations still in good shape going back twenty-five years and I still highly recommend the TD Laars as my budget model. AND it's a heckofalot easier to carry down or up the stairs.

I'm pretty sure the Lochinvar and Raypak and most low mass boilers would benefit greatly from the same precautions I recommend for TD Laars.

Bill Clinton

Crunch-Time

Were the Lochinvars that you had problems with the "Solutions" line or an older line. I understand the Solutions is newly designed. If it is the same design/line please let me know. Thanks.

Crunch-Time

Laars minitherm

Do you install by-passes on the laars MiniTherm? Thanks.

Boilerpro_3

They were the older line, haven't used any Soutions units. NM

Ron Schroeder_3

Where is the proposed installation?

Since you used the qualifier "Head and shoulders" depending of course upon your fuel of choice and system design temperature, we could probably hold our heads high.

Ike Gatlin

my job depends on it...

The Lochinvar Solution Boiler was a direct response from the manufacturer on how to solve common installation problems when using a low mass boiler, hence the name... "Solution".

The Solution boiler is standard with a built-in pumped by-pass. The advantage of a pumped by-pass over a by-pass utilizing the system pressure drop to create flow is obvious. You get sufficient flow through the heatexchanger regardless of system condition.

The Solution boiler is also standard with 2 stage firing, the 2 stage firing isn’t 2 separate thermostats controlling the gas valve, and the Solution utilizes an integrated circuit board that will operate the boiler in a low-high-low fashion. The advantage being a soft start-soft stop. Our field testing of this control showed that in a 2000 sq. ft. home, in Michigan typically had 225, or larger boiler. In a typical installation (multi-zoned, zone valves, ci replacement) the boiler actually only operated at 100% input less than 20% of the heating season. HUGE energy savings to be gained.

The 2-stage also was the solution to venting issues, instead of rapid cycling due to poor load matching, the boiler operated for longer periods of time, keeping the existing vent system warmer, and virtually eliminating condensation potential.

The 2-stage stat also offers the ability of Indoor/outdoor reset by way of a snap-on board. You do not need to use a third devise to achieve rest in your system. The cost for the snap-on board is around 200 bucks.

The Solution is also rated for a combustible floor.

All of these features are standard, out of the box items. I don’t believe you will find any boiler in its efficiency class with as many out of the box solutions as the "Solution".


Ike

bill clinton_3

Say, Ike

So you have a preferred solution for sustained low return water temperatures?

Bill

Ike Gatlin

As a matter of fact....

Bill,
I can in fact tell you, because of the built-in pumped bypass, exactly what return water temperature a system can operate at without condensation.

We dont normally publish this information because it is so system dependant, and every job is differant.

Do you have a system to try it out on?

Ike

Dave Baldwin

Some answers

I'm with Raypak, and would like to respond to a few questions raised in this thread.

We absolutely agree that primary/secondary piping is the way to go. We have recommended primary/secondary piping logic for many years, and essentially all of our commercial units have a flow switch as standard equipment to prevent no-flow firing. On residential units below 180,000 BTUH we either offer a flow switch option, or use a fast-acting temp sensor to confirm proper flow prior to allowing the unit to fire.

In addition, because flow rates are so important to low-mass copper-fin heat exchangers, we offer a pre-mounted pump option to ensure that our equipment sees the flow rates it needs.

Because of the header design we use, we can tolerate a lower return water temperature without condensing than any other major manufacturer -- no condensation down to a return water temp of 105 degF. This eliminates the need for a bypass on many installations.

As noted earlier, many of our units are bought with modulating valves that allow a turndown to 20% of full rate without condensation or burner troubles. Aside from modulation, we offer both on/off and stage-fired equipment.

And we're on the Web to answer questions. Most of our product literature is available to download from our document library, and if you need other questions answered, please contact us through www.raypak.com.

I hope the above helps.

Back-Burner_2

Modulating Valves

Is that a modulating Burner that you are referring to? And is that available on your residential boilers. Thanks.

Dave Baldwin

atmospheric burners

Um, I hadn't intended to turn this into a Raypak ad thread, just to answer his concerns.
:-)

But sure, since you asked:

Our standard burner for atmospheric use is all one part number, and is made of 430 stainless steel. We use it on on/off, staged, and modulating systems -- all our atmospheric designs except our low NOx units; they require a different burner design.

Our residential boilers are available in different firing modes dependent on the size.
From 42,000 to 66,000 BTUH, they are on/off only.
From 90,000 to 180,000 BTUH, they are 2-stage. If you prefer on/off operation, just tie the leads for high-fire together.
From 181,000 to 260,000 BTUH, they are available as:
1. modulating systems (we designate this firing mode with an "H1" prefix for temp ranges from 150-210 degF or as an "H5" prefix for temp ranges from 110-170 degF), or
2. 2-stage (designated "H3"), or as
3. on/off (designated "H4").

Bear in mind that a modulating system running at 264,000 BTUH will track loads down to about 53,000 BTUH, so a size 260 boiler (264,000 BTUH full input) can replicate the performance of all but our smallest residential boiler. That means a great deal of flexibility in boiler sizing.

bill clinton_3

several

Sure, I offer copper tube boilers as one option and regularly sell them; and yes, I would like to know the return water temperature your boiler can handle without condensing. Seems to me it would have to vary with flow rate, wouldn't it?? Thanks.

Bill

bill clinton_3

tough question for you

I'm very glad to see you guys from Lochinvar and Raypak involved in this thread. Maybe you will be willing to shed some light on a question I've long had regarding modulation. As I understand it, there are two benefits modulation is generally thought to provide:
1. Reduced cyclng of the equipment.

2. Increased efficiency.

Reduced cycling certainly happens and is certainly a benefit. I'm not so sure about the efficiency. The argument I've heard is that, since it is well known that oversizing an atmospheric boiler causes inefficiency because of the heat loss during the off cycle, and since modulation reduces or even eliminates off cycles, efficiency must be improved.

This would certainly be true if the amount of excess air traveling through the heat exchanger were reduced along with the amount of gas burned. My guess is that it is not and that the percentage of excess air increases considerably when the burner is modulated down.

So my question is: What happens to combustion efficiency when your boilers are operating at, say 25%? Are you willing to quote numbers? I know this puts you on the spot, but it is important information. Thanks.

Bill

hr

Also those low return temperatures

can show up as problems in the flue pipe. It's not just the boiler HX we need to be protecting.

Short cycles also lead to flue pipe problems. The boiler cycle needs to be long enough to "dry out" the entire flue run. I'm not sure how you can decide that from lab conditions? Every job is different.

Long flue runs, or runs through cold attic spaces need longer burner cycles to warm and dry beyond dew point.

Personally I feel a 10 minute or more burner on cycle is needed. IF the return is hot enough and the flue run is warmed.

Seems to me that adding mixing devices to boilers is a bandaid fix. Especially with so many condensing boilers on the market these days. Why not use a boiler designed for the application?

Plus the manufacture sells a higher priced piece of equipment.

hot rod

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Ike Gatlin

and the beat goes on...

Bill,

Yes, I can tell you on a specific system what return water temperature the Solution can operate at with out condensation. Yes it is system flow specific, that’s why we can’t really publish it... too many variables.

Natural Law says condensation will occur in an atmospherically fired gas fired appliance at 130 degrees. A boiler cannot be designed to defeat natural law. You can however vary flow/by-pass outlet water etc. to prevent this from occurring on the heatexchanger.

Efficiency increases in a staged fired appliance for the simple fact that the mass of the heat transfer surface remains a constant. The heat transfer area of a boiler is determined by the highest input... When the boiler is allowed to fire at a reduced input, the transfer area remains the same, transferring heat more effectively.

Combustion efficentcy is not largely affected by this... This is because the design of the burners today allow a design for secondary air to be more closely controlled. I am not remembering the numbers off the top of my head but I don’t mind sharing them. This is also the reason you won’t see an atmospheric boiler with less turn down that 50%.

Hot Rod is right... instead of worrying about "how low can it go” sell boilers that don’t care about return temperatures.

Ike

Dave Baldwin

modulating efficiency

Ah, I see the differences in viewpoint between manufacturers is showing up.
:-)

Different designs in heat exchanger, particularly header design and placement, have a significant impact on the condensation point.


Actually, efficiency slips a few percent as the firing rate drops. There are more factors involved than simple surface area of the heat exchanger. A boiler operating down at 20% of rate is at about 78% efficiency. The long answer why is already on our website as a white paper with graphs.

From www.raypak.com, select "commercial products". The left-hand menu will change; then select "Tech Corner" from the menu, and you'll see several white papers, including one titled "The Advantages of Modulation".

Our HiDelta series of fan-assisted units is available with 4-stage operation on the larger models. Our atmospheric line is available with 5:1 turndown on sizes from 180,000 BTUH to 4 million BTUH, and has been for many years. Our position remains that so long as the return water temperature remains above 105 degF, our heat exchangers don't condense.

Ike Gatlin

mines bigger

Are you talking about combustion or thermal?

Thermal increases... combustion decreases.

If the combustion efficentcy decreases, without condensation, and the thermal increases, you know thermal, the real efficiency that relates to dollars, who cares what the combustion efficiently is.

As I said, the only way to prevent condensation is to keep the return water temperature above 130. You can do this with a fancy header or with an external pumped by-pass... the goal is the same.

Any atmospheric gas fired appliance, mine or anyone else, American, German, Italian, French... CI, copper-fin, aluminum, stainless steel ALL are subordinates to natural law.

Lochinvar also has appliances that operate down to 25% input. But these are fan-assisted, and that makes it a different ball game.

Ike

Dave Baldwin

Condensation points

I really have no interest in getting into an argument about this, particularly when your company and mine have different design philosophies concerning critical design factors for the heat exchanger. Heat exchanger design affects the end result.

I already mentioned where to find the white paper on our website, and we stand by those results.


And the 5:1 turn-down I've been discussing is with atmospheric units, no fans involved. We've been selling them for many years.

Ike Gatlin

its five o'clock somewhere...

Dave,
Not arguing at all... I love conversations with others in the industry. I don’t care who you work for or what we manufacture. BTW... what’s your role at Raypack?

Coke cans and Pepsi cans condense the same.

A glass of ice water in California condenses just the same as a glass of ice water in Tennessee.

Dew point is Dew point.

Fog occurs the same here as it does in London.

Payday is on Friday.

Hot goes on the left.

The way to control condensation on a heatexchanger is by controlling the inlet water temperature. 130 is the number it doesn’t matter who you ask, how you design the heatexchanger or if the sun is in eclipse.

Ike

PS. I forgot one... Cheating on your wife is cheating on your wife, no matter what the "other" Bill Clinton says.

Dave Baldwin

Published data

People, my apologies if this sounds either sharp or curt. I offered a few thoughts and suggestions based on our published data and decades of experience, and really have neither the time nor the inclination to continue this dispute. This thread is heading away from hard data.

I'd rather get back to supporting our customers.

Instead of rehashing design issues here, check out our published literature and please feel free to send us questions via the "contact us" link on our website.

The results speak for themselves - Lochinvar heat exchangers are designed differently than Raypak, and yield different results both in the lab and in the field. We have thousands of units out in the field that work just fine with entering water temperatures between 105 degF and 130 degF. There might be traces of condensation - any heat exchanger seeing sufficiently cold entering water temps will condense briefly right at the outset. But ours don't condense enough under sustained 105 degF+ entering water temps to impact our warranty.

We publish 105 degF minimum inlet water temp. It's on our submittals and it's in our manuals.
We mean it.
We stand behind it.

Boilerpro_3

The Lochinvar literature I have talks about condensing

And it states that condensing temperature is also very dependent on the amount of excess air. As the mixture approaches "perfect combustion", the condensing temperature increases considerably. This is probably why Viessman's condensors run so efficient, they provide nearly perfcet combustion.... so it seems.

Boilerpro

Albert Huntermark

Where did my basement heat go?!!!

This summer I had a job to replace a Td-Laars. It had been in for about 25-years and until last year gave the owner practically "carefree" faithful service, and probably still would be if their old masonary chimney had not failed it! As other authors have written I agree that Td-Laars boilers have their applications and are very good products. I installed several Td-Laars in my career and even own one in one of my buildings and have no complaints about them. On this particular job, I had an issue of no heat on a Saturday evening on the coldest January day last year! The electronic pilot was lighting properly with the T-stat calling for heat and the gas valve was being powered properly, but still had no gas flow. Not: The owner had it retroffitted with an electronic ignition several years ago by another contractor. Long story short, the gas valve was bad and needed replaced. I replaced it, turned the boiler on, the burners fired up with a slight backflash. The heat spilling out of the firebox and into the room was unbelievable, as I was toubleshooting further as to why, I got a nice blister on my hand from it! After that it was easy to figure out that the flue wasn't drawing properly. The heat coming from the fire box had "cooked" the old gas valve! The old chimney was in too bad of condition to re-line. So, I cleaned the heat exchanger and the base of the chimney to get the flue to draw enough to get them heat safely through the rest of the heating season, although there was still some slight flue spillage until the chimney heated enough to draw suffciently, and a ton of condensate on very cold days. I also had to put new flue pipe as the existing was so badly rusted from the prior condensation. Since the existing chimney could not be relined with a large enough liner for the existing boiler, and the owner wasn't able to afford a condensing boiler. We settled on a conventional type that could be sidewall vented with stainless steel flue pipe. I installed that about a month ago. The last two days we had some chilly mornings. My customer's new boiler came on. She called me to let me know that the boiler was keeping her house nice and "toasty!' However, she had a question, she wondered why there was no heat in the boiler area, as she went to check the operation of the new boiler. I had to remind her why we changed it in the first place! "Oh that's right!" she giggled.