New Boiler Pipings

FWDixon

So I've now read Classic Hydronics, Primary & Secondary Pumping made Easy, and am halfway through Pumping Away so I figured I'd try my hand at drawing up how I'd like to re-pipe my near-boiler plumbing.



As a refresher, here is how my system is currently plumbed:



<a href="http://1drv.ms/MLVguR">http://1drv.ms/MLVguR</a>



So here is how I am thinking to change it to:



<a href="http://1drv.ms/MLVfat">http://1drv.ms/MLVfat</a>



Part of this replumb includes replacing the current EX-30 with an EX-60 charged to 15psi, moving the Taco 007-F5 off the boiler to the primary circuit and adding a Taco 005 to the boiler circuit, adding adding a few full-port ball valves to create service shutoffs for the various components.



Thoughts?

Ironman

Closely Spaced Tees

Your boiler connection to the closely spaced Tees is reversed.



Are you planning on keeping your present boiler and piping? If so, I wouldn't re-pipe it.



Again, you can't go changing things on an overhead system by trying to combine modern hydronic techniques with that type of system. That's a common beginners mistake.



If you're gonna replace the piping and boiler, then that's another story and p/s piping may or may not be necessary depending upon the new boiler and method of system piping employed.

FWDixon

Closely Spaced Tees and stuff

Yea, I wasn't set on whether to have the boiler circuit set as a secondary and the rad mains as the primary or the other way (thinking about it now explaining it it has to be the other way as there is no point to having the water moving through the rads if there is no heat being added by the boiler).



I'm not yet able to replace the boiler, but I am vey concerned about the low return water temps and the effect they are having (my metal flue pipe connecting the boiler to the chimney is completely shot as I found out when I removed it to clean it and it crumbled in my hands) and as the boiler is not yet leaking, I would like to prevent further damage to the CI heat exchanger.



Since I have to take the system apart to move the circ to pump away from the expansion tank, I figured I could do the repipe now and then replacing the boiler at a future time would be significantly less plumbing work. Also, it gives me more ability to service the system without draining the entire thing.

Snowmelt

Back words

The return should be comming down where the supply is. Look at it and think about it.

Also how did u come up with a 005, also what size piping Re you going to use?

FWDixon

Pump Size

125MBTU Boiler and a 20 degree delta T (180-160) gives me 12.5 GPM. The 005 was the smallest 00 pump that could get there. Figuring on using 3/4" pipe same as now (2" main pipe/2 - 1 size = 3/4") which should be negligible head loss for the

Snowmelt

Pipe size vs gpm

I am going to throw a monkey wrench in your equation



3/4 pipe you get 6.5 gpm

1 inch you get 11 gpm

1-1/4 you get 16 gpm



What you don't want is more then 4 feet per second of water flow, that's the industry standard.

Also I am going to look up btu that is allowed per pipe size

3/4 pipe 65,000 btu

1 inch pipe 110,000 btu

1-1/4 160,000 btu head



Head loss isn't part of this equation

FWDixon

Piping

I realise that, I realistically only need 65MBTU, and my burner currently is only giving me 29. So I figured if I piped for what I need (instead of full boiler output), that I would be ok with the reduced flow. Sorry I didn't state that originally.



However, I was worried about using a pump smaller than the 005 for my existing boiler since I don't have enough heat output...not sure if that makes sense but it kinda does in my head.



The 65MBTU need is based on a manual J heat loss calc and current radiation installed in the house.

FWDixon

BTU limit

Good to know about the BTU Limit per pipe size, wasn't aware of that.

Zman

Condensation

Your new drawing is not addressing the condensation issue. You have to add a bipass of some sort. A 3 way or 4 way mixing valve with an electronic controller would be a good option.You could also integrate outdoor reset with this strategy.

Do you understand why the flow directions are incorrect in your drawing? It is not because you are calling one primary and one secondary.

The pipe flow rates and btus are listed in the conversion factors tab at the top of the website.

Carl

Snowmelt

Delta t

Why don't you use the delta t pump that way you will have the correct size on your secondary side. Taco bumble bee or the 00 series delta t pump that way your space heating always has the exact 20 degree delta t

FWDixon

Re: Piping

I understand why the drawing is backwards, i have my hot water from the boiler entering upstream of the cold return water going back to the boiler.



I also have 2-way mixing valve on the diagram between the boiler outlet and the boiler pump inlet to address the condensing issues. I've thought about doing ODR on the boiler but not sure it's going to be necessary on the old CI I have and the new boilers I'm looking at come with ODR's built in.



Also, I'm curious (ironman) what problem I'm going to have with my system should I start converting the near-boiler piping over. I know you've mentioned an issue before but I would like more information if you would indulge me.

FWDixon

Delta T Pumps

Honestly because I'm just not that familiar with how these more automated pumps will work with my system. I've been told by some to stay away from the 00's all together and go back to the B&G Series 100's (and the counter that the 00's work fine and the B&G is a dinosaur that doesn't need to be considered).

Paul48

ODR & CI

In my opinion, it's not worth it with a cast-iron boiler. The window of allowable return temps is too small. Have you resolved the issue of lack of heat?

SWEI

ODR & CI

Generally agree, especially when the envelope has been improved to the point where lower fluid temps will satisfy on a design day.



There are still a few cases where it makes sense.  Fin-tube baseboard sized at 170ºF (or higher) comes to mind, along with the modified iron alloys used by Viessmann and U.S. Boiler (which tolerate lower return temps.)

FWDixon

Lack of heat

has been resolved and not.



I know the problem (the burner needs to either have the orifice replaced or the new gas control valve was not properly set after installation), but have not been able to get the tech to look at either nor attempt a repair (Why do I pay him? I don't know).



So in theory it is fixed, in practice I'm still enjoying sub 60 degree house temps when the OAT is below 25....oh well, winter's almost over.

Paul48

Meter

So, you clocked the meter and reallized you are way underfired?

FWDixon

Yup

~230 seconds to get 2 cu ft (which gives me ~31MBTU/H, (1020 btu/cu ft per my gas bill). At rated firing input it should be 47 seconds for 2 cu ft. At minimal required input (~82MBTU/H assuming 80% AFUE) should be 90 seconds for 2 cu ft.

FWDixon

Fixed the

schematic for the proposed new piping in the original post.

Ironman

Gas Pressure

Have a competent tech check your manifold pressure and set it to the spec on the burner data plate.

FWDixon

Yea....

I cannot get my tech to even look at the thing, which boggles the mind as I am paying him to do .....something......

I'll make some calls tomorrow and see if I can get someone out.

FWDixon

Called the warranty folks

back and they are sending the tech back out with the exact words you used bob written on the work order. Let's see if he does it this time...

Zman

2 Way

How are you addressing the condensation issue with a 2 way valve?

Carl

FWDixon

Maybe I'm

using the wrong name, but thinking since my boiler will heat the water to a set temp (in theory) I can position the valve to give me about the minimum desired return temp and leave it (say 140ish). As the water from the rads gets warmer, the return water will get warmer than that temp but shouldn't get below it for long durations.

Zman

2 Way

There is nothing in your piping arrangement to force the water to bipass the heat loop and recirculate through the boiler. As you have drawn it, some water will do this but you have no real control. For a simple setup you might want to look at a boiler protection valve  http://na.heating.danfoss.com/Content/8c751f1e-5476-4eaf-9df2-80d86f915668_MNU17528976_SIT209.html



Carl

FWDixon

Lazy water

it makes sense now that you say it. So a three way mixing valve like the one you linked would go at the tee downstream of the two-way valve I currently have shown and upstream of the boiler circ inlet. Then, it will operate to maintain a set temperature going in to the boiler, correct?