Big 2 Burnham boiler job coming up , need advice

Unknown

But wouldn't there be some type of efficiency loss from the transfer of heat from steam to the heat exchanger ?

Unknown

This is a big job for us

We're installing 2 Burnham V9 4 section boilers ( net rating of 420,000 btus each ) in a church . There are 5 zones of hot water heat , but I'm not sure yet what type of emitters are there . We are installing outdoor reset , but the choice of brand is ours . Hot water is made separately , but indirect heaters are always a future option we like to keep open for the customer .

We have reps from Burnham going to look over the job and decide on a control strategy , but I'd also like to pick the brains of the finest in the heating industry .

What would be your choice of handling outdoor reset , cycling the boilers in tandem , and boiler protection ? Is there a control that can do it all ? This will be our first hot water outdoor reset job , although I've done a few on steam it's a whole different animal . And are there any pitfalls we can avoid when piping the boilers in tandem ?

Once again , than you for any help in advance .

lchmb

Hey Ron

Check your email...:)

clammy

tekmar

Hey ron i've done a few larger projects like yours in the past .We used a tekmar 252 2 stage boiler controller and piped it p/s with a low limit circ controll that shuts the boiler pump off when the boiler cold till it gets to temp then turns the pump back on .Pipe the boilers into the main loop using one set of closly space tee with a reverse returns into the boilers .I,ve also found that when placing your system tee if you face them straight out and come up for your pump and check valve and turn the retrun down to form a thermal trap helps pervrnt alot of thermal migration and helps to keep air that 's circ in the primary loop from ending up back in the secondary and causing call backs for air .I started to pipe all my larger residental boiler with this in mind really stops thermal migration in it's tracks .Good luck and peace clammy

Ted_9

Idea

Clammy has a good Idea. I'm looking for a piping diagram.

Regarding heat emitters: How do you know if they will work well with the outdoor reset?

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Unknown

I was under the impression

that any type of hot water heat can benefit from outdoor reset ? My guess is there is outdoor reset hooked in already , but it's ancient and outdated so they want to upgrade with the new boiler . Any diagrams you can share would be greatly appreciated . Thanks alot Ted .

Unknown

Clammy

Would a big flow valve on the boiler return pipe work in place of a thermal trap to keep the hot water from backing out of the boiler ? If the system is suited for it , I definitely want to try primary - secondary piping . Dan Holohan personally told me the theory behind it while we both built up a boiler for the heating class Eugene Silberstein is the head of .

I've also got to think about availability of parts if something goes bad . The supply houses around here don't usually stock Tekmar , but they all stock Taco parts . Have you ever used the Taco line for outdoor reset and staging control ? Thanks alot Clammy for the advice !

RoosterBoy

Ron take a look at TACO LOADMATCH....

its a cool free program you can use and it has lots of taco goodies in it...its got things that you can do like import boilers rearrange piping add controls change piping its sorta Easy to get a grasp ...

look into it its graphics act like easy cut and paste drag and drop....

Unknown

Ron

One thing to bear in mind with this system is that we would desire that you not operate these boilers (pressure-fire V9A) with return temperatures below 135°F for prolonged periods. We provide circulator and near boiler pipe sizing in our manuals to maintain either a 20°F or 40°F temperature rise through the boiler(s). A common thing that I see with churches is the desire to keep the temperatures down until they are needed. This setback operation can bring cool water back to these boilers for prolonged periods of time. With any outdoor reset control, there is usually a Minimum Supply temperature dial or function. Normally in this case you will need to maintain at least 160°F supply water to guard against 140°F or lower return water. With these settings you are not taking advantage of the full capabilities of temperature reset, only the stage firing.

I'm sure that the reps from Venco Sales will be advising for the use of the RTC or Return Temperature Control on each of these boilers. When piped into a primary-secondary setup, these controls will allow you to take advantage of the full reset capabilities of the outdoor reset-stage firing control while still maintaining water flow through the boiler above the 135°F mark all of the time. These controls are made and engineered for us by Tekmar and work very well with the 262 Tekmar control. Here is a picture of a V9A modular application with the RTC control installed. Hope this helps.

Glenn Stanton

Manager of Training

Burnham Hydronics

U.S. Boiler Co., Inc.

Unknown

Ron

The challenge with using commercial pressure-fired hot water boilers in a modular application is how low you will be able to go with system water temperatures at any given time. Most reset controls have a Minimum Supply Temperature dial or function that you will need to set in order not to allow return water through the boiler lower than 135°F for prolonged periods of time. The problem with this is that you are not taking advantage of the full reset capabilities that the control has to offer in an effort to provide for boiler protection.

In most of the church applications I have seen, they desire to set back temperatures until they are needed. This type of operation, dependant on how far they are setting back and the type of heat emitters, can result in relatively cool return water for prolonged periods of time. I am sure that the Venco Sales boys will be advising for the use of RTC Controls (Return Temperature Controls) with these boilers as well as the 262 Tekmar control for reset and stage-firing. We developed the RTC controls in conjunction with Tekmar for use with these boilers to maintain 135°F and warmer return water in an enable you to maintain the 20°F or 40°F temperature rise through the boiler at all times of operation. We spell out pipe sizing, 3-way diverter valve sizing and pump sizing to maintain the desired temperature rise. The biggest benefit above and beyond the boiler protection is the ability to now take advantage of full temperature reset without concern of cooler return water temperatures. Here is a photo of a modular V9A with the RTC control installed last year in Ohio.

Glenn Stanton

Manager of Training

Burnham Hydronics

U.S. Boiler Co., Inc.

Unknown

Thanks Glenn

My understanding of outdoor reset is multiplying daily now . So I'm guessing that any reset curve we select , the boiler or boilers HAVE to be above 135 degrees on the return side for a significant portion of the run time ? Or is it a blended temp - whats in the boiler and what's coming back from the return has to combine for a total of 135 ?

Just thinking out of the box a little , but couldn't we just use a simple aquastat on the return pipe that would not let the boiler pump run till the temp was above 135 ? Thanks again Glenn for your helpful advice and the pic of that V9 .

Unknown

I'm gonna check that out

The Taco reset controls have also been pointed out to me , looks like a nice system . Thanks alot weezbo .

Unknown

Ron

In essense, what you need to keep the return water above 135°F is variable blending from the supply of the boiler to the return. Many do this with a blend pump which is neither variable nor a guarantee of warm return water. This is what this control does so well. An aquastat on the return is doing to stop the flow through the boiler when it is need most. The RTC keeps the injection process into the system operable while monitoring return temperature and varying the blend of heated water to keep the return above 135°F by means of the motorized 3-way diverter valve (Danfoss ESBE). Anything else such as a thermostaic valve is not neccessarily a guarantee.

Glenn Stanton

Manager of Training

Burnham Hydronics

U.S. Boiler Co., Inc.

clammy

liking thermal loops

I kinda perfer thermal traps for returns over another flow check i feel with 2 flow check could offer to much resintance to the loop if there a large pressure drop on that pump circuit plus if your closely spaced tee and coming off horitizontally it's easy to throw a 90 on it face your suction side of your supply up and return down throw a ball valve and contiune down for 24 inches and then loop back up plus the other bonus is your primary loop can get mounted with shallow versa bar and then your circuit loops and gossetts of your pumps will be spaced off the wall or panel making it easier for service and mounting .I usually use 3 /8 fllor plates and split rings or deep versa bar spaced off the wall with 3/8 sheild anchors and some 3/8 rod all washered and heavy nutted .By having the take off horizontal it keep the air on the top of the primary loop helping keep it out of the secondary and where your main air scoop or spriovent can do it's job .As for return water temp i would check your immeters and see at a temp below 140 you may find the output to be to limted .You could put a thermatic mixing valve set up to divert supply water back to the return when temps are below 140 .Hope this help you out .Ps i haven't tryed any of tacos resets in all likely hood you maybe can use one of there i series ways to by pass using there return sensor still waiting for someplace to use them peace and good luck

Unknown

Ron

If you can't get the Tekmar controls through your supply house, they can indeed be obtained through us. We market both the Tekmar and Taco controls through our product line. Taco does offer a modular staging control (PC702) which is made to plug into their zone controls This control does not have nearly as many functions as the 262 Tekmar however.

Glenn Stanton

Manager of Training

Burnham Hydronics

U.S. Boiler Co., Inc.

c.t.kay

2 boilers

just a suggestion,put in 1 8 section boiler steam,1/3,2/3 motorized steam valves,steam to water shell and tube exchanger,a heat timer to control both the boiler,valves,pumps and the reset. no thermal shock to the boiler and all the reset you want on the water side. be very careful with the mixed return water systems ,there are some horror stories about these systems around here.

Constantin

A couple of thoughts...

... many churches remain unoccupied for long periods of time but run on fairly rigid schedules. Deep setback could be a good idea.

... I imagine that you'd get some pretty hefty slugs of cold water coming back to the boilers. I like the RTC approach that Glenn mentions, though 4-way valves also work really well to protect boilers. Use the 4-way with closely-spaced T's

Constantin

Could you please elaborate?

I'm not doubting the veracity of the horror stories, I'd just like to know what they were/are so that we can all benefit from not making the same mistakes.

I'm only familiar with two boiler installations where there is staging involved. Both of them have very, very happy owners. Given that both of them use non-condensing boilers (1 set of oil, 1 set of gas) and low-temp emitter systems, the most talked-about issues of flue gas condensation, boiler rot, etc. have not materialized. The gas system did have a systemic failure though, when both gas valve thermocouples blew within a week of each other.

Had the boilers been integrated into the home alarm system, this failure would not have led to a late-night panic attack as the home temperature went south and the central alarm went off on low-temp. Had a boiler fault been detectable by the alarm system, a technician could have gotten the whole system serviced and happy w/o any interruption.

Unknown

Tekmar

sounds like the way to go . Do you know of any reps who post here that I can brain pick ? Thanks again Glenn .

Unknown

Sure

Hydronics Mike is usually here and works for Tekmar as well.

Glenn Stanton

Manager of Training

Burnham Hydronics

U.S. Boiler Co., Inc.

Unknown

c.t.kay

What on earth are you talking about?

Glenn Stanton

Manager of Training

Burnham Hydronics

U.S. Boiler Co., Inc.

Tim_16

Why would anyone use a cast iron boiler with Hot-water. Put in Raypak copper boilers..You can go as low as 105 degrees without condensation. I'm a boilermaker..Cast iron and steel boilers is what gives us lots of work. But I realize the best thing for going now is raypak. Get a reset controller that control low and high fire.

http://www.raypak.com/commframe.htm

Unknown

Raypak ?

I have to admit , I've never seen a Raypak . Do they make em in 400,000 btu size ? One thing we don't want to do is daisy chain 5 or 6 boilers .

Tim , you gotta go in to a little more detail about why Raypak is better than any other choice . How many have you installed ?

Tim_16

Ron..I have installed dozens of them..Go to the web site above and click on high delta boilers and also look at raypak..I forgot to mention also that your fuel savings with them is great..Small mass boiler versus large mass like a cast iron.

tim smith_3

RTC control and Burnham V9

Ron, I think what glenn is recommending is a good idea, use a modulating staging reset control with a RTC 3 or 4 way valve. This will protect your boiler, which by the way one of my old installs with primary secondary just lost a section, why I am not sure. And it will also provide full reset on your heating loops. I think this will be a very good system unless you want to consider 2 condensing 400 mbh boilers. Which by the way lochinvar has just come out with, although the jury will be hung on these for awhile until proof comes out in time. Good luck Tim.

Dan C._2

I have never seen

I have never seen a copper fin boiler that uses oil. I have only seen them for gas. But if it is going to be gas try RBI which is similar to raypak.

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