Rate my boiler setup

itscold29

Hi everyone, new to the site and new to boilers/hydronics.



I built a new home recently which is heated via a Lochinvar Knight WHN-055. It supplies two fan coils, each zoned individually and fed by their own circulator.



I have an HTP indirect for DHW, which is piped on its own zone.



The boiler is a closed system with a primary loop.



The system is all copper, except for the fan coils, which are fed by non 02 barrier pex, which I understand is a no-no.



However, I do understand that the DIN 4726 requirements state that it should be 50 times less than regular pex. Since our system only has about 50-60' of pex pipe, most of which is wrapped in foam and buried in concrete, I don't think it's much of an issue, considering if we had done the house entirely in buried pex we would have about 3000' of pex. Someone please correct me if I'm wrong.



There are four cast iron circulators, a system pump, dhw pump, and one pump for each fan coil. The fan coil circulators are controlled by the TACO relay box.



The DHW pump and system pumps are controlled by the boiler's smart system.



The system has performed flawlessly so far, but it's only about a year old. I know the fan coils are weird, yes, and I probably would have done pex hydronic if I had to do it again, but you live and learn, right?



We are running 140f water to the fan coils and the DHW setpoint is 125. There is no outdoor reset, as apparently in Canada most installers advise against them, due to snow buildup on them (yes, I know I thought it was kinda strange too).



So long and short, please take a look at the pictures and let me know if there are any improvements, suggestions, obvious errors, whatever that you think I should look into.



Please disregard the red and blue pex, that is part of the domestic water supply. Also, please disregard the messy 18/2 wire. I ran out of staples and will be re-routing it more neatly.



Thanks.

hot_rod

installation manual

check that piping with the suggested piping in the manual. Download one from Lochinvar site if you do not have one on the back side of the front cover.



Looks like an attempt at primary secondary piping?



As far as the non barrier tube, consider adding a conditioner, Rhomar or Fernox corrosion inhibitors would offer some excellent protection.

itscold29

ok

Yes, it looks similar to one of the layouts in the I&O manual, I can't remember which one.



It is primary with two zones as a secondary, I think?



Where can I buy Rhomar or Fernox and should I flush and fill the system before doing that?

hot_rod

it must have

a pair of closely spaced tees to be primary secondary, or a hydraulic separator (low loss header).



In this Lochinvar installation drawing the boiler has a piping circuit that leaves the boiler, crosses thru those tees in the bold highlighted box, and back to the boiler, the primary loop. The boiler pump, the black one in your pic, has to be in a loop.



I can't quite see enough of your boiler piping to tell, a drawing may be better.



If it is not piped P/S, the boiler circ and the zones circs will be in series, basically doubling the head, not the best piping method, or what the manufacturer is trying to show.



If you do not have a pair of tees piped 6-12" apart somewhere in the piping you do not have P/S piping.

jch

Orientation of expansion tank

Not a huge issue, but typically you should install your expansion tank with its inlet facing upwards so that you don't end up with any air bubbles forming in it.



Hope this helps,

.../j

jch

No hydraulic separation

I agree with Hot Rod.  There does not appear to be any hydraulic separation between your circulators which means that the performance of the system will change drastically as various circulators turn on and off.  The flow from one circulator currently fights against the flow from the other circulators which makes it very unpredictable.



As Hot Rod said, the black circulator should feed into a small primary loop with just a pair of closely-spaced tees for each secondary circuit -- in your case two pairs of tees.  Each pair of tee fittings must be within 4 pipe diameters of each other.



If you're running DHW as a priority load -- which I'd recommend -- then it needs to be in its own loop -- with its own circulator -- piped in parallel with the primary loop.  The Lochinvar would then be configured to run in that mode so that the system circulator and the DHW circulator are never running at the same time.



Does this help?

.../j

itscold29

The DHW

is on its own zone/loop with its own circulator controlled by the boiler.  It's hard to see since it's down below the boiler.



It is priority, so the boiler shuts off the boiler pump during a dhw call.



I agree with hotrod that there is no separation.  The boiler pump has a 90 right after it and then 'loops around' and back into the boiler.  There are two tees coming off of this 'loop' with the two zone circulators feeding each fan coil. (Does that make sense?)



Could I not just delete the boiler circulator entirely?  The DHW is already controlled by the boiler and the zone circulators are connected to the taco relay, which in turn signals the boiler via an isolated end switch.



Also, I was unaware about the expansion tank, I was sure the Watts manual said it could be installed in any direction.  Live and learn I guess.



About the non-barrier tube, is it really an issue since there is very little non barrier tube in the set-up?  I recently drained about half a cup of water and it was clear.

jch

Pumping direction?

Is your main - black - circulator pumping away from your boiler?  Or towards it?

itscold29

the main circulator

is pumping away from the boiler.  It is on the supply side unfortunately, which I understand is not the best way to do it.

jch

Location of expansion tank

To avoid cavitation / flash steaming in your boiler, the expansion tank should be connected to the *input* of your main circulator.  Otherwise, the pressure in your boiler could drop to negative which you definitely don't want to happen.



You should move your fill valve / air separator / expansion tank to connect between the boiler and the black circulator and at the same time fix the orientation of the expansion tank. 



You'd still need to hydraulically separate your primary circulator from your two secondary circulators with closely-spaced tees.



Does this help?

itscold29

Yes that helps thanks.

So, until I can get the piping sorted out, what are the chances of it actually flashing to steam? The fan coils run at 140f and the max the boiler will heat to produce dhw is 160.

jch

A great tutorial that should help...

I'd highly recommend that you take an hour and view this free tutorial by John Siegenthaler:

https://www.heatspring.com/courses/free-lecture-achieving-hydraulic-separation-in-hydronic-systems



That should answer a bunch of your questions.