Replace or repipe this boiler?


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Old 10-23-05, 08:16 AM
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Replace or repipe this boiler?

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 next 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. 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 at the cost of mayvbe $8,000-10,000?

I found another contractor who will repipe the primary loop for about $700.
Also, I turned off the high fire burner this weekend, so it is essentially acting as a 150,000 BTU boiler, and the house is comfortable even though the temp was in the 40's yesterday. Would maybe adding a Tekmark controller to use outdoor temp to only allow one stage to come on unless it dips below a certain temp help with our situation and allow us to keep the boiler, or should we ditch it?

Thanks. Dave
 
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Old 10-23-05, 10:06 AM
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Dave

I am not at all a fan of the copper tube boilers but at only 5 years old, I would have a hard time justifing replacement. Buderus, no doubt, is a fine piece of equipment. If it were me, I think I would go the Tekmar & re-piping route. The re-pipe has to be done anyway, regardless of which boiler you use. When you do replace the boiler, I would seriously look at a multiple boiler set up.
 
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Old 10-23-05, 12:08 PM
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Grady,
What do you think about leaving it with only 150,000 BTU operating. On supercold days if it isn't heating properly, I could always turn on the other burner.
 
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Old 10-23-05, 05:50 PM
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Low fire only

It is certainly worth a try. On supercold days, could you simply turn on the other burner?
 
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Old 10-24-05, 03:16 AM
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Originally Posted by Grady
It is certainly worth a try. On supercold days, could you simply turn on the other burner?
Yes, we could easily do that if the boiler wasn't keeping up.
Do you think we still need a buffer tank?
 
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Old 10-24-05, 05:25 PM
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Buffer tank

I would keep the buffer tank. Most low mass boilers don't like sudden vast temperature changes.
 
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Old 10-24-05, 07:19 PM
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The problemis we don't have a buffer tank, and it would be a couple grand to install one. Before i turned off the other burner, we had issues with short cycling and overheating.
 
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Old 10-24-05, 07:28 PM
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Buffer tank

I have seen, several times, an electric water heater (no power going to it) used as a buffer tank. A couple of hundred & some piping, you should be good to go.
 
 

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