Laars Endurance ebp110 adding mixing valve

HydroNiCK

Hi All,
I am primary secondary piping a Laars endurance 110 as per the below diagram. Since the internal circulator will be used as the primary pump could I install the expansion tank, air eliminator and mixing valve the same as the picture or not? I would have to install air elim/and expansion tank on the return piping since that is the closest I could get to the suction side of the circulator and then add the mixing valve to the supply pipe?

Zman

The Endurance already has boiler protection built in. Just pipe it per the manual.

HydroNiCK

Yes I know that. Its already piped per the manual. I'm re-piping it because its doing not so great protecting the boiler. Don't like that boiler or design at all. Plus, laars says it could be primary secondary piped.

hot_rod

look like the use a thermostatic union for protection? Is that not adequate?

A hydro separator would be another option. They suggest a buffer tank for small zone loads also

Zman

HydroNiCK said:

Yes I know that. Its already piped per the manual. I'm re-piping it because its doing not so great protecting the boiler. Don't like that boiler or design at all. Plus, laars says it could be primary secondary piped.

I was hoping your were not installing a new one, I don't like them either. The thermostat union is just a disk like an automotive radiator disk installed in a union. They have a tendency to clog and installers have a tendency to remove them.

Before expending too much effort on that boiler it would make sense to have a hard look at the condition of the whole unit. The heat exchangers and flues often rot out and the electronics are glitchy at best.

If the problem can be resolved by installing a new disk, that would make sense. I don't think I would repipe a pig like that.

HydroNiCK

Well, a contractor installed 3 of these boilers for a friend over 10 years ago. According to my friend and what i've seen on the wall this boiler has given many people a lot of problems. Out of the three boilers i'm dealing with the most serious problem first. The transfer tank rotted out. Now I have no idea what the previous contractor did so i've been trying to perform forensic investigation and deduction on the system. One ebp 110 serves about 1400sf of radiant plus domestic hot water. 6 loops are connected to one manifold which is fed by 3/4 pex. A section of pex runs through my friends apartment and a hallway with an exterior wall serving as entrance to two apartments. I have to have some starting point so I assumed all the loops were equal and made 3 different models which are all pretty close as far as btu and head loss go. I divided the square footage by 6 and calculated how much pex could be installed using 9"cc, 10"cc, and 12"cc. 243'(6),220'(6),243'(6) respectively. The manual says that internal circulator can do I think its 2 zones 67ft baseboard each. The apartment is on second floor tile throughout including hallway. I estimated 30k heat loss which is probably the worst case upper limit of what I need. In addition to the internal grundfos circulator a taco 007 f5 (10ft head max/23 gpm max). The boiler was condensing..pipes, water on floor everything. Now It just may need a new anti-condensing valve. However, I dont care;it's annoying. If that water is coming back too cool and the domestic hot water is removing too much heat from the transfer tank at the same time I feel more comfortable re-piping. If i add the domestic water tank to the heat exchanger on top of that then what happens? The cool radiant return will not be dealt with right away because the boiler operates in domestic priority?
I feel primary secondary provides a safe starting point and is something I can control better working with what i've got. Despite the controls that boiler has I know I can primary secondary pipe and know that i'm getting the right temperatures without having to waste time extrapolating and fiddling around.
So, having said all that i wanted to pipe the above diagram using 1" primary loop and 1" Caleffi MIXCAL 3-Way Thermostatic Mixing Valve w/ Temperature Gauge and 3/4 secondary loop with 3/4 Caleffi MIXCAL 3-Way Thermostatic Mixing Valve w/ Temperature Gauge . Change the circulator to an Alpha 2 because again i'm not exactly sure what the previous guy did and just going with 220ft loops of 1/2" x 6 at 3gpm...(220x1.5x.08) gives about 26' of head to supply the manifold which is already more than that taco can handle.

Zman

I guess if you don't have primary secondary now, that makes sense.

Be sure to remove the existing t stat disk.
Also pay close attention to the CV ratings on the mixers.