Help with plumbing boiler


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Old 08-27-14, 11:17 AM
J
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Help with plumbing boiler

Hello folks-

I bought a used Quietside QXM8 oil fired boiler from a person who switched to NatGas and I am going to plumb it in my shop and use it for hydronic heating (tubing in concrete slab) and for a bit of DHW for a hand washing sink.

When I bought it she was nice enough to include most of the pipe and fittings that were plumbed to the boiler (though some had been cut off). I've got it mostly put back together, but I noticed that it was not previously installed to exactly match the piping schematic in the manual. Here is the piping schematic from the book:



Here is a picture of the side of the boiler:


The hot water for floor heat comes out of the top fitting, goes left past the gauge, then down and right through the circulator, then down through the 1" pipe into a mixing valve, and then out through the flange. The return water comes back in below the mixing valve, where I guess some might go back up through the valve and the rest would go back to the boiler.

So, here are my questions:
1) The schematic doesn't show a mixing valve on the heating loop. Do I need that? Should I keep that, or should I just pipe right out to the heating loop manifold? The QXM has an outgoing water temperature control on the front panel, so if I can control my outgoing water temp with that, why bother with a mixing valve?
2) What is the purpose for the 1/2 inch line (with the ball valve) connecting the supply and return piping? Some kind of flow balancing or something?
3) The schematic shows the expansion tank on the boiler drain side. It looks like it had been hooked up previously to the bottom of the air eliminator, which is where I think I'll put it. Any problems with that?
4) My fuel oil tank is located outside about 35 feet away and 3 feet above the burner, so I assume I don't need a Tigerloop, correct?
5) All 3/8 OD Type L soft copper tubing sold at HomeDepot is called refrigeration tubing. I assume that is just "purer" copper and that I can use that? (No code requirements in rural Alaska.)
6) There is no circulator shown on the DHW side. I assume that is just run from the 40/60 psi water supply pressure?

Sorry for all the questions, but mostly I just want to make sure I'm on the right track. Thanks for your help!

Jeff
 
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  #2  
Old 09-02-14, 06:12 PM
D
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Most radiant heat has a mixing valve. The half inch line is probably the feed for the boiler. Connect it to the water main. You need a feed valve somewhere between the main and the boiler. You do not need a tiger loop. You don't need a circulator on the dhw.
 
  #3  
Old 09-03-14, 11:33 AM
J
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Thanks for the reply. I appreciate it. I've been doing more reading and I think I am pretty comfortable with what I am planning on doing. I bought Type L tubing which was 1/4" ID, but was 3/8" OD and was what the guy at the shop recommended for fuel oil vs refrigeration tubing. And I found out the expansion tank obviously goes on the bottom of the spriovent rather than on the drain side.

The horizontal 1/2" line coming out from the horizontal 1" line at the bottom is indeed the fill valve location. But I was wondering more about the vertical 1/2" line with the ball valve. After reading more about typical installs, it appears that is the primary loop in a primary/secondary configuration.You notice there is a flange for a second circulator on the line coming out from the mixing valve to circulate the secondary loop.

I understand the benefits of a primary/secondary configuration for multiple zone systems, but in my case I will have only one zone. Therefore, I am planning on removing the mixing valve and primary/secondary configuration and just using a simple single loop with one circulator and one heating zone. If this is a really bad idea I'd appreciate hearing about it.

My only other concern is that the spirvent and expansion tank are immediately after the circulator, and it seems standard practice to place them immediately before the circulator. Is it worth the benefit to have to unsweat those and put them back in before the circulator? I was thinking I might just leave it as-is since it has obviously ran well that way for the last 8 years.

Thanks,
Jeff
 
 

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