WEGA Mini Nova, not Heating

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
tfields30
Posts: 3
Joined: 16 years ago

#1: Post by tfields30 »

I have a Wega Mini Nova EPU, older black top model. Turns on correctly, heats to correct pressure then immediately quits heating and cools. Unit is still on. After it sits cool for awhile, it will do the samething again. I was having problems with heating and steam. I cleaned the boiler, replaced the water level sensor, have checked pressure stat (upgraded). The high limit thermostat is OK, I actually removed it to test. I checked voltage at boiler element, and I have 120, to ground even when not heating. I did not check resistance across element, I don't have a value to compare too. The element has over heated in the past. I am stumped........ Is there any possibility it could be the element, heating and opening-up when hot? Thoughts ?????? It still seems to point to the element, I have never heard of an 'intermittent' element.

Thanks
Thomas

User avatar
HB
Admin
Posts: 21983
Joined: 19 years ago

#2: Post by HB »

tfields30 wrote:I checked voltage at boiler element, and I have 120, to ground even when not heating.
I'm not an electrical engineer, but I think that about says it all, doesn't it? As for the resistance, it should be around 10 ohms according to this nifty calculator.
Dan Kehn

Advertisement
JimG
Posts: 659
Joined: 18 years ago

#3: Post by JimG »

tfields30 wrote:I checked voltage at boiler element, and I have 120, to ground even when not heating.
HB wrote:I'm not an electrical engineer, but I think that about says it all, doesn't it?.
Measuring 120V from a heater terminal to ground could be a sign of a heater problem, but not necessarily. Some machines are wired so that the switch (thermostat or pressurestat) is on the neutral side of the circuit.

On machines like this, at least one of the heater lugs is at 120V potential all the time. When heat is needed, the other lug is dropped to ground/neutral by closing the control switch.

But if one of the heater terminals is at 120V, and the other is at ground/neutral, and the heater is not heating, then that's almost certainly a heater problem (burnt out element).

If the boiler is cold, and both lugs are at 120V relative to ground/neutral, then probably the tstat/pstat switch is open when it should be closed.

Jim

tfields30 (original poster)
Posts: 3
Joined: 16 years ago

#4: Post by tfields30 (original poster) »

I tested both legs of element, 120 to ground. Yet, boiler still cold. I jumped tstat for testing purposes. Checked pstat and it was closed. I even changed terminals on the pstat, to use a 'fresh' set.

Thanks for your input.

JimG
Posts: 659
Joined: 18 years ago

#5: Post by JimG »

tfields30 wrote:I tested both legs of element, 120 to ground. Yet, boiler still cold. I jumped tstat for testing purposes. Checked pstat and it was closed. I even changed terminals on the pstat, to use a 'fresh' set.
Maybe I am missing something that is already obvious to you, but if both legs of element are at 120V, then the element would not seem to be the problem. It is only going to heat if something (i.e. pstat) brings one of the legs down to neutral potential.

If you've checked the thermal fuse and the pstat, then apparently there is something else keeping the circuit open. I don't know enough about your machine to know what that might be.

But this doesn't sound like a problem with the heating element to me.

Jim

sru_tx
Posts: 11
Joined: 19 years ago

#6: Post by sru_tx »

Thomas,
I have a Wega Lyra and it sounds like my unit is behaving similar to yours. Briefly, I turn my unit on and allow it to heat up. The unit heats up and comes up to pressure and is fairly stable after 20-30 minutes. However, if I wait too long (45 minutes, more or less), the unit starts to cool off even though it is still turned on. If I turn it off and allow it to cool for an hour or so and then turn it on, it will do the same thing all over. Is this what your unit is doing?

I'm not sure if the Mini Nova is similar to the Lyra but here's what I've found out so far. I have removed the sheet metal top cover to allow heat to dissipate more readily and to gain access to the innards. The Gicar/Giemme controller unit is enclosed in its standard plastic box plus a metal shield. I have removed both leaving the bare boards exposed so I can probe them to debug them. If I leave everything uncovered the unit will run for hours on end without fail. If I set the sheet metal cover back in place, it will overheat and shut down.

I have not changed anything yet but plan on changing the pressurestat anyways. I'm already on my third p-stat on the Lyra and have decided to put a Sirai in and forget about it. I doubt that will fix this problem. If not, I suspect a component on the controller has become susceptible to temperature and stops working properly when at elevated temps. Since I work with electronics, I will probably try to fix the controller before replacing it, otherwise, I'll replace the controller at approx. $150.

YMMV.

steve

tfields30 (original poster)
Posts: 3
Joined: 16 years ago

#7: Post by tfields30 (original poster) »

I replaced my pstat with a Sirai, no change. On the wiring, the Red is hot and the gray is neutral, correct? I measured the continuity on the neutral leg back to the neutral on the power switch, and it is open. I am leaning toward the controller too. Just hate to spend $150, to be wrong.

Thanks for the continued response !!!

Advertisement
coffee_monkey
Posts: 43
Joined: 19 years ago

#8: Post by coffee_monkey »

Any updates guys?

I have a Isomac Rituale and it's exhibiting the same symptoms as yours. Already narrowed down the problem to either the heating element or the controller... and most likely it's the controller as it's definitely an heat-related issue. Might relocate the controller box outside the machine to see if it helps...

Please keep me updated on your findings. Will report back with any discoveries as well..


- Ben
Ben Chen