R407 refrigerant

[JCole21961]

I have installed Hitachi heatpumps in my home in Brazil which use R407. The contractor is having difficulty charging the R407 so that the pressurestat protection devices do not kick out the compressors. In heating mode, with normal charge the suction pressure drops below 25PSI when temperatures are below 5C. If he adds refrigerant so this does not happen, on warmer days above 15C, the pressure exceeds the top limit of 450PSI. What are the normal operating limits for R407 in both heating and cooling modes? Is R407 commonly used? I do not know whether it is A, B or C.

[Andy W]

First of all find some one who knows what they are doing, secondly, remove all the gas in an environmentally friendly manner, dehydrate the system, weigh in a fresh charge as detailed on the data plate, work out how metres of pipe you have and add the required gas per metre. It should then work perfectly, if it doesn't you have a problem elsewhere. Don't forget to weigh the gas in in the liquid phase and not vapour, use new gas not reclaimed or recycled, surely your "contractor" knows all this any way, if he doesn't he should not be messing.

[frank]

I have installed Hitachi heatpumps in my home in Brazil which use R407. The contractor is having difficulty charging the R407 so that the pressurestat protection devices do not kick out the compressors. In heating mode, with normal charge the suction pressure drops below 25PSI when temperatures are below 5C. If he adds refrigerant so this does not happen, on warmer days above 15C, the pressure exceeds the top limit of 450PSI. What are the normal operating limits for R407 in both heating and cooling modes? Is R407 commonly used? I do not know whether it is A, B or C.

I think it's D

If you are not careful you will end up with a U/S compressor (no, that's not one made in America)

[tricky ricky]

most hitarchi units come in england pre loaded with 10m worth of gas depending on model we add approx .19kg per metre over 10m.

[Brian_UK]

It gets you worried, doesn't it Frank ??

[Snowman123]

You'll need abot 4.5 to 5.0 bar suction pressure.

[JCole21961]

Thanks. What are the normal upper and lower pressure values for R407 under the normal extremes of weather in heating and cooling mode? I have read in another report that R407 is about 40% less efficient than R22 in cooling mode. Is this true?

[frank]

I have read in another report that R407 is about 40% less efficient than R22 in cooling mode. Is this true?

Not quite true. R407C is fine for medium temp applications and is about 5% less efficient when compared to R22.(Obviously there is also the glide factor to consider). When R407C is used for applications with evaporator temps lower that +5C the efficiency really starts to drop off. I've got a few detailed research notes on the subject but I'm sure you can find it on the net by "Googling"

[Brian]

Hello Frank! They are now designing evaporators which are better suited to R407c's glide and they can actually benefit from it! But still, when all is taken into consideration, they are'nt as efficient as an azeotropic blend.

[frank]

Hi Brian

Did you get my e-mail?

R407C? - Its getting to be old hat now

[chilly]

We need model numbers of both the indoor and outdoor unit, The size pipe you have used and the pipe run distance (one way).

Hitachi utopia units are fantastic and always work when installed correctly (well almost always)

Its imperative that the charge is correct, For this you need to dehydrate, and weigh in the correctly calcul;ated charge.

I'll post the correct weight of R407c if you post the details I have asked for.

As already mentioned you need to charge in liquid phase. And make sure you are experianced in refrigeration or ac, if not you should get an engineer in otherwise i dont hold out much hope of the system surviving much more abuse.