Buffer tank control

1sttimeposter

Hi
We have a Tekmar 306V valve controller connected with six room thermostats and six zone valves.

The manual is pretty clear on how to set up our IBC SL10-85 G3 to sense water temperature in the 2-pipe buffer tank to turn the boiler burner on/off based on ODR curve. Boiler pump and tank sensor are wired directly to the boiler.

But not sure how to trigger the secondary pump to turn on to draw warm water from the tank to the zones when room thermostats call for heat or off when satisfied?

There is no specific instruction in the manual about it. How would I I wire the secondary/system pump to the Tekmar or/and the boiler for this part? Do I also need the boiler pump to come on if burner is off when room thermostat calls for heat.

thanks much for your input

109A_5

I'm not 100% familiar with the Tekmar product line, looking at the manual for the Tekmar 306V valve controller, is that the correct box for your application ?

If the boiler senses the tank temperature and maintains the tank temperature and controls the boiler's circulator. The Tekmar 306V controls the secondary circulator with a call for heat from a thermostat .

Buffer tank not pictured.

Jamie Hall

Are those zone valves? If so, they are powered or controlled by the thermostat associated with the zone. That opens them on a demand for heat. They also have an "end switch" which closes when the valve opens. If you have just the one pump, those end switches are all wired in parallel and thus when any end switch closes the pump runs. There is a joker in the pack: often the zone valves are 24 VAC, while the pump is 120 VAC, so you need a relay which is closed by the end switches and which, in turn, powers the pump.

109A_5

Maybe something like this.

1sttimeposter

https://forum.heatinghelp.com/discussion/comment/1853221#Comment_1853221

Thanks a lot. That could be it as I do see a 'SYSTEM PUMP' connection on that Tekmar 306v. So that should trigger the secondary pump (sp) when room thermostat calls for heat. but now what about boiler pump (bp)? Do I need bp running too when sp is running?

109A_5

Folks like @hot_rod could probably better answer that question better than I can. I would think if the boiler is monitoring the temperature of the buffer tank and heats it appropriately with the outdoor reset. When a thermostat calls for heat it does not need to also run the boiler's circulator. If the tank temperature drops enough the boiler will start and the boiler will run its circulator to heat the tank. That way you get the best performance from the use of the buffer tank.

mattmia2

is this already plumbed? how you control it will depend a bit on how you plumb it.

1sttimeposter

yes, the two pumps are there already and looks something like this:

109A_5

If the boiler needs a demand signal to operate the X-X of the Tekmar 306V would go to the appropriate input on the boiler.

hot_rod

The boiler pump should be wired to run from the boilers own control relay. So when the boiler contact is "made" from the tekmar, that boiler pump will energize.

The tekmar powers the system pump.

1sttimeposter

Thank you both hot rod and 109a_5.

So far this is what I understand, please correct me if this is not the ideal and operation arrangement for my setup:

*If no call for heat by room thermostat - IBC senses the water temp in buffer tank (bt) for burner to turn on/off with operating boiler pump using ODR while system pump should be idle;
*if call for heat by room thermostat, zone valve(s) open(s). And regardless if IBC is heating bt or not, both pumps should be operating.

All six room thermostats are all wired to corresponding zone valves in the Tekmar 306v. System pump hooks up to Tekmar's 'SYSTEM PUMP' connection. bt's sensor as well as boiler pump are wired directly to IBC's respective connection ports. Lastly, Tekmar is xx'ed to IBC.

Kaos

Quick read. Doesn't look like you need to connect the Tekmar to the IBC. It gets the load from the temp sensor:

https://www.ibcboiler.com/support/TIPortal/Content/Installation_&_Maintenance/Knowledge_base/PDF/Tech_Bulletin_Heating_Loads_by_Sensor.pdf

This makes sense, it is how you want to run this type of setup as it decouples the boiler cycles from space heat cycles.

109A_5

Which sensor is in the buffer tank ? The secondary loop sensor, one of the Therm inputs ? No real buffer tank configuration is in the I/O manual.

1sttimeposter

I concur with you Kaos that all of the buffer tank's water temp control logic can all be achieved within IBC control setup.

But if indeed I need the boiler pump to operate as well as of course the system pump when room thermostat calls for heat, if buffer tank is not being heated at the same time, how can I make the boiler pump to run if we don't x-x Tekmar to IBC?

1sttimeposter

https://forum.heatinghelp.com/discussion/comment/1853320#Comment_1853320

IBC labels buffer tank as 'Secondary Loop' and the sensor is called 'Temp. Sensor'.

I can see the buffer tank' water temperature in the app. named 'Secondary Temperature'.

109A_5

" But if indeed I need the boiler pump to operate as well "

Think of it as two independent systems. The boiler maintains the buffer tank temperature and the boiler controls the boiler's circulator. When a zone calls for heat the second circulator is activated by the Tekmar 306V to circulate water from the buffer tank through the calling zone.

The only time the Tekmar 306V would need to connect to the boiler is if the boiler needs a demand signal to fire at all. It is all about what modes of operation the boilers software will support.

You may be able to satisfy a zone never even firing the boiler, just drawing the heat from the buffer tank. That way when the boiler does fire the boiler's run time is longer and more efficient.

I have not yet reviewed the document Kaos cited.

Another way of looking at it. if a zone calls and the boiler fires, all the circulators needed heat the calling zone run, what do you need the buffer tank for ?

hot_rod

if the buffer is up to temperature and a heat call comes on, there is no need for the boiler pump to run

Properly piped, the buffer tank is the hydraulic separation device. You have two separate piping systems, sharing the same water and storage space

Your decision is which control to use as both the tekmar and boiler have over lapping control functions

I use the boilers control to do as much as possible as it has a large screen to view and adjust, probably does some data logging, and alarms certain fail conditions and reasons. So most all the functions are in one location

A basic relay box could power the zones