Here are the symptoms, what is the problem? circs too small?

[MrEd]

I am using a version of the simplest pressurized plumbing layout for my tarm 60 - with the exception that my storage is not on-line yet.

Very happy with the results so far...can keep the house at 70+, but then again it has not been really cold yet...

Here is a "problem" that I want to figure out.

Just as the design calls for, I have two circs. One on the tarm, and one on the common line from storage and from the tarm, so in effect since I have no storage on-line yet, both pumps are on the same line running in series. They are Grundfos 15-58's both running on high.

The house has 5 zones, I can easily heat 3 of them at a time, I can do a fair job heating 4 of them, but if I open the 5th zone (also happens to be the biggest with about 100ft of baseboard), the house doesn't come up to temp quickly or easily. (Luckily this 5th zone is a basement loop which really doesn't need to run much if at all).

My first feeling would be that the circs are not big enough, but given that I am running a 200K BTU boiler, flat out, it has never idled a single time yet - in other words enough heat is being moved away from the boiler to keep up with the output, makes me a little skeptical that just increasing the size of the circ will help.

Ideas? This is not a major problem, but would be nice to tweak the performance some - and no, I have not done a full heat-load analysis yet, started one a while back and seemed like a long confusing process so I stopped- but given the symptoms I am describing, any guesses?

If your guess is that the circ is too small, based on symptoms can you tell if I need more head? or more flow? would the symptoms be the same either way?

 

[Nofossil]

It would be interesting to get temps into and out of the boiler, and at the return side of each zone.

As you say, if the boiler isn't idling then you're extracting all the available heat from it. The basement zone alone can suck up something like 60,000 (or more) BTU/hr. Perhaps that's too much given your other loads.

Two key data points - good to get numbers with and without the basement zone:

1) What water temp is the boiler delivering?

2) What is the return temp from the house zones?

This will help determine what's going on. I for one would try slowing down the load circ or maybe both circs to get the water temp up a bit if it's not coming out of the boiler at at least 170.

 

[MrEd]

I am going to have to break down and by either an IR thermometer, or a bunch of mounted ones. Its true I have no good info to go on. Its been on my list to do...

The boiler panel tells me its running at at least 170 and more often 190-200 most of the time(once it gets cranking), so I would assume its coming out the back at those temps - return temps I have no idea so I'll need to get better info to diagnose.

 

[Nofossil]

I am going to have to break down and by either an IR thermometer, or a bunch of mounted ones. Its true I have no good info to go on. Its been on my list to do...

The boiler panel tells me its running at at least 170 and more often 190-200 most of the time(once it gets cranking), so I would assume its coming out the back at those temps - return temps I have no idea so I'll need to get better info to diagnose.

If you're seeing 190 to 200 at the boiler outlet, then I'm thinking that the circs are too small. Do you have any restriction in the system other than the zone valves? I don't know the guidelines, but I expect that 60,000+ BTU/hr is a LOT for a single zone with a zone valve. You'd want 6 or 7 gpm through that zone alone, and that may be more than a standard zone valve can easily handle.

 

[MrEd]

The big basement zone comes off the boiler, into a "T" and then there are two seperate loops, back thru a "T" and then back into the return line. Its all 3/4 copper and was all here when I bought the house.

If its the only zone on, it works just fine, just doesn't get much heat when everyone else is calling for it (which in my application is actually a perfectly OK scenario).

Just ordered a IR thermometer from amazon - it'll be here tommorrow (gotta love amazon).

Not sure what other restrictions you had in mind - there are some strange looking fittings that I have only seen on my basement loop. There is one on each side of the 2 "sub-loops" just before they come back into the "T"

 

[chuck172]

Ed, I'll bet the basement zone is too long for 1 zone. I think you maxed out of distance for 3/4 copper fin tube. You may have to divide it into 2 seperate zones.
I'm sure someone in the business can let you know what the max. length of 3/4" fin tube can be.

 

[MrEd]

I suspect you are right - its been that way for 45 years, but I don't have the need to change it. I can live with it only "kind of" warm in the basement.

 

[WRVERMONT]

Running a 200K BTU boiler, flat out, it has never idled a single time. There would have to be adequate flow through the boiler for this to be the case. Unless the wood is of a low output type, etc. Curious to see how this turns out. Maybe after a longer burn the boiler would eventually go to "idle". Interesting.

 

[Nofossil]

Running a 200K BTU boiler, flat out, it has never idled a single time. There would have to be adequate flow through the boiler for this to be the case. Unless the wood is of a low output type, etc. Curious to see how this turns out. Maybe after a longer burn the boiler would eventually go to "idle". Interesting.

He IS getting to 200 degrees, though. I don't know what temperature initiates idling - can't be much hotter than that.

By the way, MrEd - use masking tape 'targets' on your pipes for the IR thermometer. They don't work on shiny metal targets like copper pipe.

 

[MrEd]

I'll have more info later today - thermometer is due in this morning.

BTW: The wood is soft maple mostly, that's what I have so that's what I burn.