Circulator on secondary loop runs almost nonstop

[Rugar]

My eko is outside with aprox 60 foot of inch ID pex connected up to the intake manifold of my old gas boiler. I'm using the old circulator on the gas boiler as my secondary circulator controled now by a strap on aquastat. The secondary circ now with eko runs almost constantly. It use to only run a few min to fifteen or so when it was controlled by the old gas boiler. Is something wrong and do I need to re-plumb.

More info if it matters is my primary circ is a taco 07 controlled by the eko.

further info is that I find it almost impossible to overheat my house. I have old baseboards.

 

[Gooserider]

My eko is outside with aprox 60 foot of inch ID pex connected up to the intake manifold of my old gas boiler. I'm using the old circulator on the gas boiler as my secondary circulator controled now by a strap on aquastat. The secondary circ now with eko runs almost constantly. It use to only run a few min to fifteen or so when it was controlled by the old gas boiler. Is something wrong and do I need to re-plumb.

More info if it matters is my primary circ is a taco 07 controlled by the eko.

further info is that I find it almost impossible to overheat my house. I have old baseboards.

I think the problem is the 1" PEX - you flat don't have the tube volume needed to carry the amount of BTU's that you need to heat your house... If your pipe insulation isn't 100% perfect, the problem would be even worse...

Do a search on sizing for pipes between boilers and heating locations, you will find a bunch of stuff on this, it is a VERY common mistake made by many.

I also found some really good info on this while looking at the Bioheat website - they talk about their boilers, but the same ideas apply regardless of brands.

Gooserider

 

[Chris S]

Also, your original boiler was probably supplying 180 degree water into teh supply header. With the distance, and the (possible) flow issue, are you still getting that.
The OWB vendors would sell you a larger pump

 

[Rugar]

My boiler is set at 195. If i remember correctly the line just past the mixing valve heading away from the boiler room is 179 and after the 60 ft run to the house at the intake manifold on my old boiler it's something like 177-178.

 

[Gooserider]

We really need more info than what you are supplying, such as your heat load figures, and possibly a plumbing layout for how you have stuff plumbed.

Baseboard also tends to require higher water temps than other hydronic emitters in order to perform well, unless you have seriously oversized the amounts installed.

I still think the issue is most likely undersized pipe on the run to the EKO - what is your RETURN temperature coming back into the boiler? It sounds like you are producing enough heat at the EKO, and you aren't loosing huge amounts getting to the house, but heat delivery is a function of both the water temperature and the volume - you have only so many BTU's per gallon at a given temperature, so if you aren't getting enough gallons, you don't get the BTU's either...

Traditionally, fossil boiler setups were generally designed to give a design day temperature drop of about 20*F between the boiler supply and return temps. If you are seeing a much bigger drop than that, it would indicate that you aren't getting enough flow volume as the flow that you do have is dropping a greater percentage of it's heat...

Unfortunately, if this is the case, then there are really only two possible cures -

1. A bigger pump that can push more volume through the existing lines - downside will be higher electrical expenses, and possibly increased noise and wear on the plumbing.

2. Increase the tubing volume by either replacing the existing runs with larger bore tubes, or adding a second set of 1" tubes in parallel with your existing tubes - I'd probably go with the latter as >1" tubing seems harder to find and much more expensive.

Gooserider

 

[Rugar]

I get 7-15 degree drop in temp max on the return water. I have an old 1000 sq ft two story house with little insulation. I've estimated heat load to be 30-35000 on the max end. I back that by the prior year when I would burn 7-10 gallon of propane per day. The boiler is outside in an old building with a 60 foot run of inch al pex. The pex that has a true inch inside diameter. Bought it from Cozy Heat. The Boiler circulates with a taco 07 cartrage pump. It's a primary loop that circulates to a manifold on the old gas boiler. This loop is madeup of two closely spaced T's with the return on one side of them and the other side is the inlet to the circulator that pumps the secondary loop or the entire house for that matter. it's the old system circulator and I didn't change anything on it. All I did was add the closely spaced T's between the return and supply.

I'm sure I made this real confusing.