Converter for 115VAC, 60HZ to 230VAC, 50HZ sine wave up to max. 100Watts.

[Jos van Doorn73]

Hi,
I'm looking for some help on the issue as mentioned in the tread.
I would like to build a converter in order to have a modern processor controled, gas heated, water heater that will only work on a 50Hz sine wave (as tested - with a small generator - it does work A-OK) in a country where the mains supply is 115VAC, 60Hz.
The generator is not an option as it is much to noisy and we dont use hot water during most of the day.
Many years ago I have build a converter for a friend to provide 115VAC/400Hz and that worked just fine but was probabely much to complicated and was only for a small power source and for a demostration.
It used a crystall controled oscilator circuit and several opamps to convert the oscilator frequency to 400Hz sine wave and than a power amplifier module to transformer for the output but I think that that is too complicated for my application.
I have seen professional converters but they are far over my budget and look like killing a bug with a sledge hammer.
The manufacturers customer support of the water heater does not reply to my help request and only limits to tell me to contact the nearest technical support and that is in Germany and my water heater in Nicaragua so....not very helpfull.
(no thanks Vaillant!!).
Basically I asked them if there was not an option on the control board to make it work on 60Hz (There is a strapping on the board shown in the block diagram as S1 but it is not documented in the installation manual and I dont want to blow a brandnew heater) but no more answering after my querry on the strapping.
My cuestion obviously is....anny bright ideas how to build a converter???
Thanks,
Jos.

 

[BobK]

Must be a small water heater if it only requires 100W.

Are you sure it requires 50Hz? Typcially, anything that does not involve motors does not really care much about 50 or 60 Hz.

Bob

 

[davenn]

Must be a small water heater if it only requires 100W.

indeed, VERY small

Are you sure it requires 50Hz? Typcially, anything that does not involve motors does not really care much about 50 or 60 Hz.

Bob

agreed ... a heating element wont care if it is 50 or 60Hz
so all you need is a transformer to convert the voltage and then consider your timing control to switch power to the transformer on and off as required


Dave

 

[73's de Edd]

.

Sir Jos van Doorn73. . . . . . .

Initially referring to the :

I would like to build a converter in order to have a modern processor controled, gas heated, water heater that will only work on a 50Hz
sine wave (as tested - with a small generator)

And thereby, the "gas heated", disqualifying the MUUUUULTI kilowatts being required for a heating element.


Check out these possibilities:

Instead . . . the need of a typically 24VAC gas control valve . . . . . and the info on any associated parts still dependent on your looking at the Vaillant unit and passing
on to us, its model number, in order to see what further info may be gleaned from it . . . . . for YOUR particular unit.
Some Vaillant models seem to be using a model numbering scheme of VUW 282 and 286 or TURBOmax Pro 2E.
An example of the latter . . . . . .

If you were thinking of the microprocessor taking a 60 or 50 cycle sample relevant to its time base, I believe that design need went out with the late '70's---'80's.
Typically there is a microprocessor using a very commonly used freq of 4 Mhz and a ceramic resonator used to supply it .
Small transformers should get a slight relief when running at 60 vice 50 cycles as well as small synchronous motors, with their slight increase in output speed.


Refer to this units typical 130 watts AC power consumption, on page 4, as well as the most heavy power consuming parts of:
(On page 57)
Item #1 fan, (note that motor type . . . . . which would accept 60~)
Item #13 pump
Items #14,15,16

http://www.gotogasdocs.co.uk/f/m/Vaillant/Boilers/Turbomax VUW GC 47-044-26 282E.pdf


Now one thing that you have not told us . . . is IF this unit is ADDITIONALLY circulating water for radiant heat purposes . . . . . to a room (s).
In referring to page 20 you see a CONVENTIONAL clock timer is being involved , for selective disabling of heating for a time period thru the day (night time sleeping).
THAT motor type is a place where using a VERY low power frequency pure sine converter 60--->50 ~ would be involved . . . . such as you have had experience with in the past..


If you use two of the type of transformers that let you select paralleled or series primary's, you should be able to wire to get 230VAC out from a 130 VAC input by using transformers
with power levels of a bit more that the 130 watts specified.

Research to see if this info makes sense in your situation.


73's de Edd.

 

[BobK]

Ah, I missed the "gas heated" part.

Bob