Hey

I have the same problem as Giotto not maintaining boiler pressure, but the thread is old and not accepting replies anymore.

The heating element is very unreliable and does not activate every time. Some times I have to flick the switch a couple of times to get it going. The pump is working, so the tank sensor is OK. I think its a bad relay in the control box. The control box has 3 relays, two small a5 (G5NB-1A-E-DC12 Omron) and a big a30 (G8P-1A4P-DC12). Am I correct in the assumption that I need to change the big a30 one?

Here are some pics:






Best regards
Rasmus

Your troubleshooting seems spot on to me. The big relay would be the one that switches the element current and it would be prone to failure because it carries a big load. Failing pStat contacts might in theory cause the same problem, but your pStat doesn't carry much current. On my older ECM (different controller) I had the same symptom (element sometimes stops coming on, and a bump of the machine or a flip of the toggle gets it heating again) and it was caused by a bad power relay that switches the element. I sent mine off to jpboyt, who inspected/tested the controller and replaced the bad relay.

Also, some people have advised changing to a different controller and wiring scheme, so that none of the relays in the controller carry a big load. Good advice if you are buying a new controller. But if you're going to keep that controller and just replace the relay, what you can do is add an external relay to handle the element current and just let the one inside the controller drive the control of the external relay.

I did that to mine, just using an inexpensive ice cube conventional relay. ( Diagnosing Dead ECM Giotto ) Was cheap and easy, and I wasn't sure I had space for an SSR and heat sink.

Hi. Finally received the relay. Everything is working again, so I guess it was indeed a bad relay. Not sure I am going to go the extra mile and put in an external relay tho.