Laars Minitherm?

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Old 01-05-09, 10:00 AM
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Laars Minitherm?

Hi,

I'm wondering what the general opinion is on the Laars Minitherm. (http://www.laars.com/webDocs/docDownloads/1086H-NH.pdf) I've had several boiler installers out for quotes, and the installer I liked the most recommended the Laars. I haven't heard of Laars before, but I don't see too many complaints out there. Would you agree? Is this a decent boiler?

I'm looking at getting either a JVS75 or JVS100 installed in my house. I've gone through the heat loss calc (trying to take out all conservative assumptions), and the JVS75 just barely meets my needs for my design temp of 0F (Denver, CO) with compromises already factored in (such as we won't be able to heat the uninsulated basement zone to even 65F at an outdoor temp of 0F or lower). I'm hoping I'll be ok in that I saw that AFUE ratings assume the system is oversized so perhaps I'll get more output from the system when output = heat loss. I'm still on the fence on size, but I am definitely thinking of going with the Laars.

Any opinions/advice are appreciated.

Thanks.
 
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Old 01-05-09, 05:27 PM
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Frogg, pretty much any boiler is only as good as it's installation. There have been some 'dogs' over the years, but for the most part they all do what they're supposed to do.

Laars are a slightly different 'breed' though... they have copper tube heat exchangers in them, and as such they are VERY SENSITIVE to proper flow through the boiler. The manuals state that a SYSTEM BYPASS must be piped when installing to insure enough flow through the boiler so that the Delta T across the boiler is correct. If the bypass is left off, you can have premature failure of the boiler, and Laars will NOT honor a warranty if this is the case.

If your installer likes Laars, he should know this...
ask him to install a temperature gauge on the boiler RETURN in order that the delta t can be monitored and the bypass valve correctly positioned.
 
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Old 01-06-09, 07:13 AM
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Thanks for the reply Trooper. Your comment about the bypass is interesting too. One of the guys who came out to give us a quote said that Laars are universally bad based on the number of failed units he has had to pull out. He mentioned the bad units were all installed by the same company. It sounds like they probably weren't installing the bypass.

F
 
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Old 01-06-09, 10:46 AM
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AFUE is not based on over sized units. It is a test done on the product running at 120 return temp and 140 supply temp. If the boiler is over sized when installed your AFUE goes right out the window. Size the boiler from your heat loss to the DOE Output. If your real close remember there is fluff built into heat losses and if zones you have extra fluff.
As trooper stated it has to do with the installation. More boilers have failed due to improper installations. The best boiler operation is properly sized and piped per manual. That is why they come with the boiler so we know how to pipe the new boiler.
 

Last edited by NJT; 01-06-09 at 03:32 PM.
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Old 01-06-09, 03:33 PM
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I thought those installation booklets were to kneel on so we don't get our pants dirty!
 
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