Replace or Repipe?

Dave_61

I have someone lined up to repipe it and place the bypass in the right place. He will charge me about $700 to do that, along with cleaning up the primary loop.

What do you guys think about my turning off the second stage on the boiler? It is currently running with just one stage of the burner operating. It has bben in the high 30's the last 2 nights in a row, and the house is comfortable.
Can I possibly get away with running this boiler just on single stage and then it will only be putting out 150,000 BTU's? I also switched the DHW to priority on the Taco controller.

Everything seems well.....is it possibly this simple? If, in the dead of winter, it can't keep up, I can always turn the second stage back on. What do you think of my experiment?

Dave_61

Replace or Repipe?

I'm really at a loss.....We have a 5 year old house with a low mass Lochinvar copper tube boiler. It is about 6000 sf and is well-insulated, has plastic vapor barrier and top of the line Pella windows.
From the beginning, we have had problems with our gas boiler (never piped right). It is a 300,000 BTU unit and when it runs, it tends to run for about 2 minutes before shutting down. Then it is off for 2 minutes and then restarts all over again. It also is noisy at times, sounding like a low-flying jet.
It has a 2-stage gas burner which is basically controlled by whatever operating and high fire temps we set it to on the dials. We have high fire set at 155 and operating temp at 175.
Attached to this unit, we have 3 hydroair fan coils, a Phase III indirect water heater, and a small radiant floor loop for the master bath.
I had a heating company come look at repiping, which would probably take a day to do. Originally, the technician recommended just repiping the primary loop. However, the nest day he called and said that after discussing it with his boss, we should replace the boiler with a Buderus.
When I asked him why, he said that the low mass copper tube boiler will always make noise in our application, and we won't be happy with it. Also, we have had a problem with the boiler pump seizing several times, and he said this would probably continue to happen in our current setup even though I think it's because the pump is too big (Taco 0012).
With the price of gas going through the roof, I am not totally against replacing the boiler. We intend to be in the house for at least 20 years. But is it truly worth it to replace it? Or would somehow adding a controller to use outdoor temp to only allow one stage to come on unless it dips below a certain temp help with our situation?
Thanks.
Dave

Robert O'Connor_12

Dave

Something doesn't sound right. Are you sure the pump is working and installed in the right direction?

Robert O'Connor/NJ

Dave_61

pump

The pump direction is from outlet to inlet, but it is a huge pump that is only being used to pump water through the boiler loop. The original installer put it in because he thought we weren't getting enough flow across the haet exchanger (we were getting noise).

RoosterBoy

Dave, do you have a picture?

sometimes it is eaier to give an answer that way, as it may bring a clearer understanding of a solution more quickly.controls should also be included in the picture....any blue boxes or maroon boxes for example would give us a clue as to whats what. if the electrical goes to a series of pumps to the fan coils then a picture of them might be handy also. if you have away to get the combustion make-up air openings into the mix that would help too.

Constantin

I'm at a bit of a loss here...

... you say that your house is well-insulated, yet your contractor installed a 300kBTU/hr boiler in a 6,000 sq. foot house? Is this a greenhouse in Alaska? That's 50BTU/sq ft! No wonder the unit short cycles...

Given how long you expect to live in this house (20 years), I would get a reputable company to do a heat loss (or use your gas bills as a first-order approximation), then have them install a condensing, modulating boiler per the manufacturers specifications. You should be able to re-use the Phase III, but the near-boiler piping will likely have to be changed to accomodate the new boiler.

I would expect at least a 30% drop in the gas consumption rate, nevermind the increase in comfort if you go with a condensing boiler. Naturally, this is easy to say since I'm just a homeowner, not an installer. However, if you look through the many reports back from the field, most condensing boiler installs have saved their customers 35-43% fuel on a heating-degree-day-adjusted basis.

If you like your present heating contractor and want to stick to Buderus, ask them about the GB142. Arguably a step up from there is the Viessmann Vitodens series, which features a stainless HX instad of the Aluminum one found in the GB142. However, if your present heating contractor installed the 300kBTU boiler presently found in your home, I would strongly consider clicking on "Find a Pro" to get a second opinion and/or quote.

Dave_61

Constantin

What about the issue with the hydroair coils requiring higher water temps and a condensing boiler like the 142? I'm not sure if the hydroair coils are large enough. The first and second floor units are 80,000 BTU's each, and the third floor unit is 60,000 BTU's.

Dave_61

Here's a picture Weezbo

Here is a picture of the main boiler setup Separate pumps all come off suypply manifold. Whenever any zone is calling for heat, the main boiler pump also runs. The only controls are Taco relays for pumps:

Constantin

Sounds to me like the coils are oversized to begin with

What is the total capacity of the coils vs. the rest of the heating system?

If you have 300kBTU/hr of emitters installed in a home that is unlikely to lose less than 120kBTU per hour on a design day, you'll be able to run those emitters at a much lower temperature than 180°F and hence still take full advantage of a condensing boiler. Besides, even a system that has been sized for 180°F on a design day will still run at much lower temperatures for much of the year if it's allowed to take advantage of outdoor reset and the like.

Dave_61

coil capacity

I guess total capacity of coils would be 220,000 BTU's (80 + 80 + 60). Plus we have the DHW indirect and a very small radiant loop.
I was also told by an installer that if the water temp is say only 140, the air coming out of the vents would feel cold.
Is that true?

RoosterBoy

Constantin has a good point.

there are Ceilings of abnormal heigths with all wall glass and the like in some large homes so it maybe short cycling due to more conventional construction with low heat loss. are there many bedrooms and baths or swimming pools hot tubs or snow ice melt discussed in the original proposal?

Dave_61

We have a 2 story family room and foyer. All other rooms on first floor are 10 foot ceilings. We have an average amount of glass (no huge walls of glass).
All rooms on second and third floor are 8 foot ceilings.
We have 6 BR's (3 on second floor, 3 on third floor).
We have 4 full baths (actually 3 at present as 1 full bath has not been finished yet) and 1 half bath.
There is no pool or snowmelt system, nor was one discussed.
At the time the house was being built the original heating contractor had specified a 250K unit, but then he bumped it up to 300 for some reason.

Constantin

Fascinating...

... most residential hot-air ducts are specified with the assumption of 115°F air in them, IIRC. I don't see how the air could feel cold until it was colder than the ambient air temperature, i.e. ~70°F.

Only a pro who is there can say for sure, but from my end of the internet, it looks like the entire system is grossly oversized. On the other hand, the huge emitters are to your advantage, and the distribution manifold looks like it was done nicely. Thus, the amount of repiping may be minimal.

Ron Schroeder_3

short cycling

is the result of more BTUs being released form the fuel than either the building envelope can absorb and lose, or the circulator can move away from the appliance. Constantin was right to suggest that you might have a slight discrepancy between the actual heat loss (if one was done) and the capacity of your boiler.

With a building/emitter combination such as you have, it is not correct to oversize the boiler for domestic hot water production. Domestic hot water can be nicely provided by means of priority switching, between heating cycles, as it were.

Long story longer, the boiler is likely too big. The large circulator that is churning water through the boiler is probably also contributing some heating effect to the water.

Condensing boilers can be nicely integrated into hydro-air heating systems. Just keep the air handlers running and modulate the supply water temperature for comfort.

Dave_61

Here's the bottom line...

Ok. Thanks for all the advice, guys. It has helped me feel a little better. SO here are the (2) million $ questions (I hope I don't offend anyone with the second one):

1. Should I bite the bullet and put in an appropriately sized boiler? (The contractor who's coming will be doing heat loss calcs).

2. I am so fed up and angry about the amount of money this will cost us, not to mention the aggravation of listening to the noises this boiler has been making as well as being without heat at least 3 times in the past few years.
Do I have enough of a case for a lawsuit against the original contractor?
Thanks
Dave

jerry scharf_3

same exact thought

Dave,

I had the exact same thought as Constantin. You say your house is reasonably well insulated with no unusual heat loss characteristics. From this I would expect a heat loss in the 15-20 BTU/sqft for design day. This puts your boiler at 2-3 times the guestimate for the house. If you have the time, I would download the free Slant/Fin heat loss calc program (see the pipe on the upper left) and do a heat loss calc on your house.

Even with this, 2-3 minute cycles probably indicate a delivery problem. If your current boiler is running at 80%, that 300MBH burned produces 240MBH in hot water. If we use the 20 degree delta t between supply and return water temperature, it conveniently works out to 10MBH per gpm (gallon per minute) of water flow. This means you need to have 24gpm flow (a pretty big number) at that delta T or the boiler temperature will begin to rise. The lower the flow x deltaT, the faster the temperature of the boiler water will rise.

It might be that the right sized boiler would make all the problems go away, but we can't know. You really need to get a pro who knows boilers and hydro-air out there and figure out what is going on.

hope that helps,

jerry

Dave_61

Jerry, what do you mean by delivery problem?
Do you mean the piping situation?
I have 2 guys coming out next Friday to look at the system, along with the Buderus rep to see if maybe their boiler would be a better fit.

jerry scharf_3

\"delivery problem\"

Dave,

You start with hot water in the boiler, and you want to end up with warm air in the house (for the hydro-air case.) You are using a pair of transport media to accomplish this, the water going to the air coil, and the air being pushed to the room. I use the term delivery for this.

I hope the following isn't too pendantic.

I happily stole the idea that the transport medium works like a train on a loop. The BTUs hop on at the boiler, and hop off at the emitter in the room. Your BTUs need to make a transfer at the hydro-air coil. With your high capacity boiler, you have the the factory whistle on a friday afternoon. All these BTUs come rushing out of the boiler. Those BTUs need to be delievered to their destinations. If the train isn't fast enough or carry enough passengers, the boiler gets congested. If the transfer station doesn't handle moving the BTUs onto the other trains, the train comes back half full and you again get congestion at the boiler. If the transfer station has great capacity, but the second trains are not fast/big enough, the transfer station jams up, the BTUs can't get off and the train comes back half full. All produce the exact situation you describe.

There is a situation called steady state, where all the power inputs and losses match. In this case, the temperature doesn't change anywhere in the system (the rooms are part of the system.) On-off controls can't do this, so they load the system with extra energy for a while then coast and lose energy. You're seeing what I consider to be an abnormal case of this.

As for the boiler, I think it's less an issue of the color of the jacket or the internal design and more one of size. Don't get me wrong, we can discuss vendors and designs long after anyone else has died of boredom, but you seem to have more basic problems.

jerry

jerry scharf_3

My $.02

my answers are:

1) you should fix the system. You've identified the boiler, but it may be only part of the problem. I would have a basic redesign done, figuring what is and isn't working now. Go into this open to any possibility, with a clear desire to reuse as much as possible. That's not a million $ question but may well run you thousands.

2) I feel your pain. It's very frustrating for you and it's also frustrating for the people here who know your job could have been done well the first time.

I am not a lawyer and I never played one on TV. I think the money is too large for small claims court, and to small for the expenses of general litigation (see above.) If the person had a company that has since been dissolved (not so uncommon in the trade,) there may be nothing to sue anyway. The idea that these folks get away with it is part of the absurd way the building trades have evolved. Same goes for people who refuse to pay for the job that's done.

sorry again,

jerry

Dave_61

Thanks Jerry
Looks like I'll be looking into getting the new boiler.
But as far as the question I asked earlier, if the heat loss calculations that the new installers do show that the boiler is way oversized, would I have enough ammo to bring a lawsuit on the original designer of the system?
It will probably cost me about $10,000 for the new boiler and hookup, and we have had nothing but headaches for almost 5 years.
Thanks again.
Dave

Constantin

I am not a lawyer...

... and I'm also not sure that your efforts are best put into pursuing the original installer rather than pouring your energy into a system that will keep you warm and happy for the next 20 years.

I understand your anger and can empathize, but the bottom line is that 5 years is a long time to wait until voicing this kind of complaint, your installer may be out of business, etc. I suppose you could hire him to remediate the problem, i.e. give you a really good deal on a proper install, but why tempt fate twice?

Dave_61

He's still in business and has had several people out here in the past trying to rectify the situation, but if the boiler's too big, no amount of bandaid solutions would solve the problem.
BTW, he totally disagrees that the boiler is oversized. He says that no one else but us has had a problem with their system. Of course, ours was the first of this kind he installed.

Unknown

Could the boiler circulator

be pushing water through the primary loop faster than the secondary loop can grab it ? I'm rereading Primary-Secondary Pumping Made Easy by Dan Holohan right now . It looks like you have 2 closely spaced tees to the secondary loop , which is all the heating zones ? It also looks like the secondary loop is direct return ? Meaning all the supplies are off of one tee on the primary loop and all the returns are off the other close tee ? I wonder if this was the proper way to pipe the loop ? Forgive me if it's the wrong theory . I'm only up to page 20 or so . Can you tell us the make and model of the boiler ? Do you still have the installation manual , and does it specifically say how to pipe the boiler ?

Dave_61

Ron,
All the pumps are off the same supply manifold and all return via the return manifold.
I still don't think the primary boiler loop is piped appropriately. The boiler is a Lochinvar EBN 300. It looks like there should be 2 closely spaced tees in the primary loop and the supply manifold comes off one while the return comes into the other. The piping schematic from Lochinvar can be found on the following page.

http://www.lochinvar.com/product.asp?cat=B&cls=ALL&prod=EBN150&ln=EPLUS#

Alex Giacomuzzi

Some Other Thoughts........

Here are some other considerations you might like to weigh.

You mention that you have a 2 stage burner. This could be helpful. What is the BTU input for just the first stage?
Do you see where I am heading? If you have enough BTU's you could possibly run the unit on low fire or stage 1. I would check this possibility with the manufacturer of course. You could dial up the high fire set point to were it is out of the control circuit. Should be an easy test.

Another question I have after looking at the "by pass" piping near the boiler ----- Is this the recommended location suggested by the manufacturer? This location could allow the HX in the boiler to heat up even faster as described above..... resulting in a faster shutdown. Worth checking into.

What is the system pressure that you have your system at? I am trying to understand why you are having pump seizures. Are these seizures only in the boiler pump or also with some of the others? Consdier 20 psi on the system.

Now ---- the main problem is a miss match between what your boiler puts out and which emitter or emitters are calling. Think of all the possibilities of combinations..
Scarry to figure out a control scheme to deal with this. There might be hope "IF" you are interested in keeping your existing boiler. Consider a large ---- 80 to 120 gallon well insulated buffer tank which gets heated by the boiler water on its own loop. Lets say you maintain the buffer at water temperatures between 140 to 180 deg F. You may want to have the boiler directly supply the buffer tank and the Phase 3. Now all the other zoning and pumping comes out of the buffer.......... not the boiler. The boiler only turns on when either hot water is calling or the buffer tank water is at 140 deg F. The cycling should improve considerably. Is there a possible way to derate or lower the input to this boiler??

Just some thoughts to soak on.........
Regards Alex

Unknown

The system tees

look like they're in the right spot . I think the system supply and return are OK . The instructions show the boiler circulator pumping into the boiler though . Yours is pumping away from the boiler . They also show the air eliminator , expansion tank and feed valve after the system tee , not on the boiler primary loop . Not sure if that is causing the problems though .

RoosterBoy

Soory Dave....I had to bail...

well,we just spun in a 215 5 section and lashed it up to some Thick SOG and dialed er way down and will call it good till tamale*~/:)

Ok So the Ladds have given you an idea or two,just as i was about to post a reply this morning ai the blasted phones are ringing...me an the mouse in my pocket getting Berry Berry sad for this...here is what i thought to run by you,first of all thanks the picture makes conjecture a group easier.one thing though due to the angle of the dangle i couldnt quite grasp what is happening in a couple places in the piping arrangement,however, one of the things that you might think of is stepping the return from the radiant down one more level ,the pumps you have seem sorta on the large size then again i have no real clear mental picture on how far these btus must travel,i have seen similar insalls that work fair enough however we have somewhat newer controls that do a variety of things for ones comfort,they work well with the SR 506 or whatever that you have now...our more recent boilers are squeezing the last Dime out of the oil guys and gas companies profit margin ) well would you belive..not making them exactly happy....:) Also when you are having heating and cooling and outside air all pretty much spun in under one control electrical energy management figures into the picture as well. Thats about what i had rolling about in my brain cell this morning...

With higher costs and higher temp waters the choises are becomming more and more evident,lets get away from wowee temps in the boiler and fields and thin down the raging blast furnaces attempting to heat the great outdoors go for moderating temps down in the fields modulating the burners down at the boiler,dialing the flow down to meet the need with variable speed ,dialing the delivery systems down to whisper, maybe entertaining the idea of solar the next couple years For DHW and maybe we will find a bit more comfort in the future...woops...when you consider boilers some are spendy on first glance as are the controls..still,what is available now are some really This century looking appliances the phase III is not a bad deal when looking at things it seems to me some new controls,some slightly different piping arrangement,and maybe a new boiler would be dollars well spent.

You could rearrange some of the piping ,add a buffer tank,use some injection mixing ,expand the controls and you would be getting a slightly better overall system. i tired as it were...been up reading since like 4 so hope this helps, In regards to suing people ...it doesnt pay...the lawyers the only one going home with the dollar...Dont encourage them....

Dave_61

OK,
I did what Alex said and turned off the high fire control, so my boiler is essentially now a 150,000 BTU instead of a 300,000 BTU monster. All hydroair zones are running today (40 degrees and rainy). The water temp is set at 180 degrees.
And the house is very comfortable.
Would it maybe make sense to repie the primary loop for the $750 or so someone quoted me and possibly add a controller like the Tekmark? I may be able to get away with the one burner running even on the coldest days heer in CT as our heat loss is about 135,000 BTU for the house (5 years old). Or should I think about replacing this boiler with a condensing one for about $8-10,000? This one is supposed to be 84% efficient.
Thanks for all the advice.
Dave

Dave_12

Buffer Tank

Consider adding a Buffer Tank to the system. The boiler is obviously oversized, especially if only one zone is calling for heat. A large tank will serve as a place to build up a heat reservoir that can be drawn from.

Furd

buffer tank

There is no question that the existing boiler is vastly oversize for the "normal" outside temperatures encountered. Of course the design must take into consideration the worst case scenario and be able to maintain comfort on the coldest day expected all the while not being too large during more moderate temperatures.

This boiler contains a very small amount of water and so it is extremely fast responding but it also has little capacity to moderate when full capacity is not needed. The adequate performance with the second stage burner "locked out" proves that the boiler is too large for "normal" conditions.

I heartedly second the idea of a buffer tank, the larger the better, and to have ALL of the secondary loops be supplied from, and return to, this buffer tank. By experimentation you can find out how low a temperature you may run in the buffer tank and still adequately serve all of the secondary loops. By having a relatively large on-off differential from the boiler to the buffer you will minimize the short-cycling. Be sure to set the "on" setting of the second stage burner to a temperature lower (by ten or more degrees) than the normal low temperature cut-in point. Addition of 3-way temperature modulating valves on the secondary loops (you may already have these) will also help.

This system could also benefit from a microprocesser-based control system that would adjust all the different temperature requirements in accordance with both inside and outside temperatures.

All of the above would also be beneficial with a smaller boiler. The one thing in favor of the existing boiler is you certainly have the capacity to add on to the system and there is no doubt that it will keep you warm in minus 60 degree temperatures.

Heavy

Remove some sections


I did not take the time to read everyone else's comments, but I saw that you think the boiler is oversized. So, rather than throw it out and start over why not break it down and remove a section or two (or three) to get it to the right size. Then all you would need to buy is a new jacket. Anyone consider that?

bob_50

By-pass

Dave it looks to me like the bypass is on the wrong side of the primary loop pump. You have system water by-passing the boiler, this will make the boiler short cycle and make noises like an elephant in heat. bob

Alex Giacomuzzi

Turning off the second stage is a simple test indeed.

BUT -- it may not be an APPROVED long term operating situation recommended for your particular boiler. Only the manufacturer knows this for certain.

Given all the safety awareness that we are practicing, "PLEASE"-- call the manufacturer and discuss the situation with them. For long term operations of the boiler in a reduced burner mode, I would hate to see you put your family's safety at risk for the sake of a test of a cycling boiler.

Regards Alex

Dave_61

Furd,
Where could I get say a 80 gallon storage tank that won't cost beaucoup bucks? (brand, etc) Thanks.
Dave

Dave_76

Alex,
I called Lochinvar, and they said there is no problem with leaving the second stage off. So, I guess I can act currently as a manual boiler control and leave that second stage off until it can't keep up (say on really cold days).
Who knows.....maybe it will be able to keep up all winter long.
Thanks.
Dave

Dave_61

Alex,
So I picture the tank in series in the primary loop. Water will have to flow into the tank to get back to the boiler. Then from the primary loop, just past the tank, there will be two closely spaced tees that will supply the supply and return manifolds, (basically out of the tank). Just like how my system is now with the supply and return manifolds teed together in the loop. In other words, just out of the tank, there would be a tee that goes to the supply manifold and then attached to that tee in the primary loop would be the return water from the return mainfold (both tees would be connnected in primary loop). Would that be right?
Would the Phase III stay attached where it is?

Constantin

A cheap way to do it...

... is to take an electric water heater tank and use that as a buffer. Pipe the boiler into the electric element portholes (I think they're 1¼"), then pipe the house off the remaining taps. Flow through the remaining taps might be an issue though, so I'd check to see that the size won't be a problem.

Alex Giacomuzzi

Hi Dave:
I will try to explain how I would pipe it.
Take the boiler completely out of your existing loop piping momentarily --- mentally or on paper that is.
You want to have the buffer tank supplying all your existing heating usage points (possibly excluding the Phase 3 that is). What this piping would look like is the top of the tank would be piped to your supply manifold. You would have the tank, an air elimination device and Extrol Tank then a pump, then all the usage supply points.

The return piping would go to the bottom of the buffer tank. In other words .... there will be a loop with the buffer tank in the middle between your supply and returns.

Now for the boiler..... I would pipe the boiler separately to the buffer tank with the appropriate flow check valving in both the loop above and in the boiler loop. You do not want the boiler to be in series with anything but the buffer tank. I would (if possible and if there are enough tapings in the buffer tank ---- probably about 1-1/4" in diameter) supply the heated boiler water to the bottom of the buffer tank and take my return from the top of the buffer. This does two things, it gives you better forced mixing and it returns warmer water to the boiler to help you maintain the minimum boiler water return temp. Do not forget to still plumb in a bypass to protect the boiler. If you are limited to the amount of tapings in the buffer, you could possibly install a Tee at the top and bottom along with the necessary flow checks in both legs to have the system work.

Regarding the Phase 3.... I do not remember the size of the unit that you have. Depending on how your house uses (or looses) heat and how much water needs you have for your family it could get piped in one of two ways. First of all I can not determine how it is presently piped --- sorry.
The two possible ways would be to pipe it in parallel with the other hydro air units with a priority DHW setting. This would allow the energy in the buffer tank to be used, but temperatures within the tank could be slightly lower than you may like --- so this should be a consideration. The other method would be to pipe a primary secondary loop (2 closely spaced Tee's) into the hot water side coming from the boiler (and going over to the buffer tank) and still use a DHW priority setting on your controls (which I presume you may have).

Regarding Buffer Tanks........ A good source to consider is a well insulated electric hot water tank that has the appropriate tapings.

I hope this helps and good luck.

Regards Alex

Dave_61

With only one stage of the burner running (so we're at 150,000 BTU vs 300,000 BTU), the boiler now seems to run for about 4-5 minutes before reaching operating temp.
In this situation, do I even need a buffer tank?
BTW, Lochinvar tech rep said that it is fine to run boiler for proloinged times on 1 stage. I may be able to get through all but coldest winter days on 1 stage. So would a buffer tank be necessary?
Dave

Dave_61

Seems like all the electric hot water heaters of that size (80 gal) have 3/4" or 1" tappings. My primary boiler loop is 2" and the manifolds (supply and return) are each 1 1/2"

Jon Gerstad_2

Bypass wrong...

That's what I thought, Bob!
As long as Dave's "Pumping Away"