WM ultra series 2 controlled with Tekmar 423, 0-10VDC reset control.

ch4man

I have a job coming up to replace a shorted Tekmar 423 universal reset control whose screen is now blank so i cant see what the old settings were, so i need to start all over. in reviewing the I/O manual for the 423 one parameter is for the minimum control signal to set the lower range for the 0-10VDC signal and to set it of the mfg requirements.
I will call Weil Mclain but thought I'd start here first. is it just a matter of figuring a percentage based on boiler turndown and apply it to the 0-10vdc signal such as a 5 to 1 turndown (20%) and set the minimum to 2vdc or to lightoff RPM to avoid run issues?

Zman

This is where you find them under service bulletin. http://www.tekmarcontrols.com/products/hvac-systems/422.html
I only see series 3, is yours older than 2011? If so you may need to check with Tekmar or WM

ch4man

thanks Zman, i did find a reference to the ultra series 1 & 2.
http://www.tekmarcontrols.com/images/_literature/sb0032_02.pdf
but..... it also states no need for an adaptor. the series 2 & 3 ultras use the old venerable HW mcba5 control and my customers installation is using WM AM4 adaptors (0-10vdc in to ribbon cable out into the mcba5)
sooooo, I dont think ill believe Tekmars SB as being 100% error free

ch4man

bump?
anyone, anyone. Bueller, Bueller?

Turbo Dave

Tekmar technical support has been very fast in answering similar questions for me.

Zman

I would call Tekmar and see what they say. I think the info is in SB031 which is not on there website. Chances are the settings for series 3 will work but you should double check.

ch4man

just an update.. Weil Mclain tech support says the minimum firing rate signal from a 0-10VDC analog signal should be set to 1.8.