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Re: Taco SR506 Switching Relay: thermostat Calls for Heat but zone not activated
I am thinking that one of the relays on that board are acting up. there are seven 24 VAC coil relays and one 120 VAC coil relays. I believe the one with the metal strap all the way to the left is the 120 VAC relay
Grainger sells the replacement relays for that board. Grainger # 6C875 is the 24 VAC one. Grainger # 6C876 is the 120 VAC coil relay. But it has been so long since I worked on that older model. I can't be sure if my information is current. I thing one of the 2 relays on the left are the problem. and it looks like that problem has happened once before and someone robbed zone 4 relay and swapped it to fix a problem in the past. Just a guess.
If you can give up one of the zones for now and you take a zone relay out and swap it with the second from the left relay, you may solve the problem. Then you can order the #6C875 from Grainger to replace the failed relay.
@SteveSan From TACO Tech Support is on here regularly, and he will know if one of those relay cubes will solve the problem you are describing.
Re: Taco SR506 Switching Relay: thermostat Calls for Heat but zone not activated
" I also measure the voltage of the relay coil terminal when zone 1 is called. The coil of ZC ZR got high voltage (~14V) to activate but all other relay coil including zone 1 got low voltage (~0.8V). "
The 14 volts measured without even the load of the relay coil in the circuit may mean a poor connection, a relay contact that is tired, worn or oxidized or an oxidized switch contact from never being used. The 7 relays are 24 VAC coils. There is not much on that circuit board, it it was a poor solder joint you probably could physically agitate it by flexing things.
I would use the ohmmeter function to test the NC contacts of the 120 VAC relay, then verify the coil is 120 VAC and if you can safely apply 120 VAC to the coil and test the NO contacts.
109A_5
Re: Taco SR506 Switching Relay: thermostat Calls for Heat but zone not activated
OK. it is getting late here and I don't want to miss Santa's visit:
In order to get heat for tonight, connect all the circulators to operate constant. set one of the thermostat to call for heat so the burner will run. when the thermostat is satisfied, the burner will shut off and the boiler temperature will drop as the circulator pumps move the water thru the system. You can do the same for the DHW circulators. Once you charge the tank with DHW from the boiler, you can disconnect the circulators so the DHW does not get too hot.
Re: Bleeding boiler system for radiant heating?
it depends on how much fluid you loose while making the change. Do you have a way to catch and pump the glycol back in?
An auto purger may get any air out, if you have one,
How old is the glycol? Do you absolutely beed glycol?
hot_rod
Re: Bleeding boiler system for radiant heating?
Turn the thermostat all the way up for a couple of hours.
leonz
Re: Steam condensate tank defective float switch.
While still on the subject of this float switch and converting to the screw - in type, be sure you choose the Form Z20 type. The non-Z20 type uses a 3/16" Buna quad ring to seal the pivot rod. Buna is suitable for use with water and most petroleum products, and is good for 220* F. temperature.
The Form Z20 uses a Viton quad ring seal which is also good for water and most petroleum products, and is good for 400* F. temperature. These are longer lasting in high temperature applications.
The problem with both of these elastomers is neither is recommended for use with Amine based boiler water treatment chemicals.
A recommended elastomer for use with Amine based boiler water treatment chemicals is Ethylene Propylene Rubber, EPR, which unfortunately the switch manufacturer, now Telemecanique, does not offer. EPR is good for up to 300* F. EPR elastomers are not recommended for use with petroleum products.
When these quad ring seals begin to leak, these 3/16" quad rings in EPR elastomer material are available from McMaster Carr in quantities at a very low cost.
Due to this Amine compatibility issue, I have had customers require that I furnish condensate pumps with EPR seals. Shipco is one pump manufacturer that I know of that as standard uses EPR elastomer shaft seals on all their condensate pumps.
As a practical matter, I have never seen a Buna or Viton shaft seal that failed due to the presence of Amines. I guess this is an issue of Amine concentration, PPM. I have asked several suppliers of Buna and Viton elastomers at what concentration would Amines cause breakdown? So far, nobody has been able to answer this question.
Pumpguy
Re: Steam condensate tank defective float switch.
I agree with @Pumpguy rather than wait for an outdated switch make a new plate. A machine shop or fabricator can do it if you don't have the tools, get the newer style switch and be done with it. You will probably need one from Shipco or make one.
Buying a LWCO to make the temp fix will cost a fortune
Re: Short cycling boiler. I'm stumped.
If the pin is missing for whatever reason you can take it out of the old fill valve and install it in the new one if you have to.
Re: Servicing Honeywell Braukmann TRV
The valve bodies all seemed to be fine. Worst case the valve seal may need replace but the ones I’ve examined look good. Wish I’d got before I added the two radiators in my shop a couple years ago!
Re the Thermostatic actuator knobs; I’ve tried on a couple of my rads but no go. I expect there’s some compatibility issue with the newer valves. I’ll test with your old valve bodies sometime and let you know.
Regardless, all well worth the “free to good home” price paid. 😎
PC7060