Boiler Pump and circulator flow control problem

Pelletduo60

Hello all first post here.

I have a home with a Euro-made Pellet boiler project that was started and i have been trying to finish it to get it working this winter. The contractor i had recently hired set up a primary loop with a pump that has a thermostatic 3way valve with auto bypass.

The issues i have are the secondary loopwith the 3 zones. He had put in 3 circulators and we have been using this set up to heat. the problem is when the boiler shunt pump is going on primary loop then the zone circulators are letting fluid by and the other zones are getting heat when there is no call to turn them on. I dont see the circulators he installed are fitted with flow control valves.

Im trying to go at this my own now and fix the problem. What are my options? Do i replace the circulators with ones that control and stop that flow until turned on when called for heat? or do I replace the circulators with zone valve controllers?

Thanks for any help and let me know if any other details are needed.

EBEBRATT-Ed

I would think those pumps have check valve in them. You may need flow check valve to prevent ghost flow.

I would like to see all the piping to see what is going on.

Pelletduo60

EBEBRATT-Ed said:

I would think those pumps have check valve in them. You may need flow check valve to prevent ghost flow.

I would like to see all the piping to see what is going on.

Ok here are pics of the rest of it going to the boiler. Would a flow check valve be installed on each loop or 1 before all three circulators?

Steve Thompson (Taco)

I'll bet if you feel the pipes on the inlet and outlet of each circulator (obviously while they are running) there will be almost zero temp difference - translating to very low delta T's as a result of over pumping. Suggest you set the speed on the boiler circ and zone circs to a lower setting. Let the system react for a few hours and feel the pipes again.

EBEBRATT-Ed

You would need a flochek on each pump. But try what @Steve Thompson (Taco) posted first

hot_rod

You also have a circulator in that return protection module, it may be pushing past the zone circulators even if they have checks

 Since  you have isolation flanges why not remove one pump and see if it has a check. If not you could add them, look like a common Grundfos manufactured circulator 

hot_rod

here us how I would pipe a system like that with a buffer tank or hydro Sep. That eliminates having the boiler pump and zone pumps in series. Do you have a buffer tank? Most solid fuel boilers need them.

often times the boiler pump alone is all that is needed, it depends on the type of heat emitters, piping method, etc

Pelletduo60

Steve Thompson (Taco) said:

I'll bet if you feel the pipes on the inlet and outlet of each circulator (obviously while they are running) there will be almost zero temp difference - translating to very low delta T's as a result of over pumping. Suggest you set the speed on the boiler circ and zone circs to a lower setting. Let the system react for a few hours and feel the pipes again.

Boiler pump is set to the lowest setting i tried that. The flow still passes by the circulators less then before but still passes.

hot_rod said:

here us how I would pipe a system like that with a buffer tank or hydro Sep. That eliminates having the boiler pump and zone pumps in series. Do you have a buffer tank? Most solid fuel boilers need them.

often times the boiler pump alone is all that is needed, it depends on the type of heat emitters, piping method, etc

Thanks for the input. When i read the boiler manual it states it doesn't require a buffer tank as the boiler itself has a tank of 43 gallons. I also have a 60gal indirect water tank that holds 10 gallons or so on the boiler side so overall storage is close to 50 gal.

I have no issue replacing the circulators with zone valves if that will solve the issue. like you said i think too i just need only that boiler protection pump and no circulators.

the main supply lines all have individual pex Al pex/02 pex lines going to 3 zones 1 zone is indirect water heater, zone 2 is forced air 100kbtu exchanger and 3rd zone is radiators and radiant floor that hasn't been installed yet. What i am not sure about is the return line they put in. It is a Pex B main line return. so all zones intersect at some point in line with the main return that comes back into boiler room. Does each zone have to come back to the boiler room or can this be left alone as is for the return?

thanks

hot_rod

As I see it your boiler pump in the module and the zone pumps are in series, adding head to one another. The boiler pump, when bypass is closed probably pops open any checks you may have 

Get the model number off the boiler pump to see what it has to offer for flow and head. The boiler has near zero pressure drop, a few feet in that mix valve, so you typically have enough circ for both boiler and system. Doing some math would confirm that.

Pelletduo60

hot_rod said:

As I see it your boiler pump in the module and the zone pumps are in series, adding head to one another. The boiler pump, when bypass is closed probably pops open any checks you may have 

Get the model number off the boiler pump to see what it has to offer for flow and head. The boiler has near zero pressure drop, a few feet in that mix valve, so you typically have enough circ for both boiler and system. Doing some math would confirm that.

ok pump said it can be set to 4m Head up to 7.5m and flow is 12gpm to 17gpm. it is set to the lowest setting. So main return PexB is fine how it is? I didn't know if every return line had to come back to the boiler room. We are dry walling in 2 weeks and won't have any further access to the return lines after.
Thanks for the help on this HotRod

Pelletduo60

Also the reason i ask about the return and plumbing layout series vs parallel is I am adding a chilled water heat pump later this year and want to have it run in the same lines as it can both heat and cool. so it will be supplemental heat in winter and a primary cool in the summer.



This is the unit.


This is the closest design

hot_rod

I don’t know if many heat pump brands that don’t require a buffer tank, maybe a few with variable speed inverter compressors. Check the installation manual. A buffer tank would help for the boilers also as a bit more flywheel and a way to get hydraulic separation between that return protection module Xander your zone pumps

what type of emitters do you have to run the chilled water thru? Dew point will be a concern for most radiators, radiant panels, anything but fan coils

Pelletduo60

I will get a buffer tank and add it to the boiler room. The dew point will be my hardest challenge for sure. I have looked into the components and controls for sensors and they get spendy. Tekmar i believe has the best options i have seen. I will have heat-only zones and bypasses on the radiators and radiant. I plan to use only fan coils for the cooling season one in our loft 500 sqft. The rest of the 3000 sqft will be off the main central air heat exchanger zone. I am also planning to run a radiant zone that will strictly be for research purposes to play with the dew point and sensors. I may end up needing to have a few more fan coils if it gets too hot.