General > General Technical Chat
Need an expert statement
Sauli:
Perhaps I should have put this in the Jobs board, but the General Technical Chat board seems more active..
I have at home an air-to-air heat pump. One of those with an outdoor compressor unit and an indoor heat exchanger unit. About 1.5 years ago the indoor unit was replaced. This was covered by the quarantee. But the next winter it turned out that the device stops heating when the outdoor temperature drops below -15 degrees. The company who sold/installed the the unit tried to diagnose/solve the problem on several occasions during the winter. The last thing they did was change the electronics control board of the indoor unit from the one intended for middle European market to a one for Nordic market. However, this was so late in spring that there no longer were cold enough weather to cause the heating to stop.
Last Decebmer this control board change proved to be useless, the problem remains.
Now we are at a point where I have raised a dispute with the seller. The problem is that since the quarantee has expired it is my responsibility to prove that the device is not working correctly. In addition to the seller questioning that there is any problem with the device he is claiming that that any problem is self caused because I have modified the device.
And now we are getting to the cause why I am writing this message. So, I must be able to prove two things:
1. That the device stops heating at cold weather.
2. That it is not caused by my modification.
Perhaps worth mentioning that it makes no difference whether the indoor unit uses it's original NTC sensor or my modification. Heating works just fine unless the outdoor temperature is too low. The seller claims that the modification has broken the indoor unit electronics in such a way that causes this behaviour.
The modification is that I have replaced the NTC indoor temperature sensor of the indoor unit with a programmable resistance. The purpose of this modification is to move the measure point from the indoor unit to the living room area where we mostly spend our time. This is about 5 meters from the indoor unit and the measure result is transferred by radio to the indoor unit where I have added the necessary electronics. Now I need a qualified electronics engineer to give an expert statement about how probable it is that the modification has done some damage. I know a couple ones myself, but they are deemed biased just because I know them. I have also contacted several companies here in Finland who write expert statements to insurance companies about household appliances, but they all have refused or ignored me. Perhaps they are not much of electronics experts. Not knowing where to turn next, I decided to try this forum for help. So, if there is anyone willing to give a statement, please let me know. I will provide documents for the basis of the statement. And you don't have to give it for free.
Carel:
I am not an expert, but I remember the stopped functioning of a refrigerator in a shed of a neighbour during winter. After scratching my head and Googling it turned out to be an indoor refrigerator. The filling gas/fluid is different.
I am such an expert that I had to Google air to air heating:
https://www.daikin.eu/en_us/product-group/air-to-air-heat-pumps.html
And yes, if I had a heat pump, it would be useless for you. (lower on the page, optimised heating 4).
So far, my non-expert opinion.
jonpaul:
Bonsoir monsieur Monsieur good problème
Needs photos and block diagrams of entier système
A few questions please
What's the cost of the entire installation?
Did you read all terms of,sale and warranty?
How much does a lawyer in your area charge per hour?
Normally any manufacturer warranty is void if the unit or installation is modified.
Could your different temperature sensor and wiring affect the control board?
Bon chance
Jon
dietert1:
At how low temperatures do you want to use the unit? There will always be a technical limit.
I think in a dispute about engineering, one needs recorded measurements as a base for reasoning. In this case probably logs of machine states (temperatures inside/outside, power consumption, pressure whatsoever). Does the coolant freeze below -15 °C? Is there snow/ice covering the outdoor unit? Can the electronics provide these data?
For our photovoltaics installations i once bought a 2x serial to ethernet converter to grab the data and feed them into our network. In Germany there are no real winters anymore, no more snow, rarely below -10 °C.
Maybe the company can also provide those logs, better avoid another dispute.
Can you undo your mod until the problem is clear, maybe get the inhouse box replaced by the company?
Also you could try to find an alternative product and in this process get some idea what may be wrong with the existing one. Are you the first one in town to try that heat pump? Maybe a small roof above the unit could help.
Regards, Dieter
coppice:
--- Quote from: Carel on February 11, 2022, 02:53:11 pm ---I am not an expert, but I remember the stopped functioning of a refrigerator in a shed of a neighbour during winter.
--- End quote ---
There are lots of problems with fridges and freezers in cold conditions. Most models have a note saying they are not suitable for use in sustained cold conditions, but they don't usually make this note prominent. They aren't talking about Siberian conditions, either. Many say they are not suitable for sustained operation at <10C, once you have found the detailed statement. If you intend to site a fridge or freezer in an unheated location in a cold country its best to check for an explicit statement about just how cold the site is allowed to be.
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