Advice required for novice please

Old 11-24-16, 02:25 PM
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Advice required for novice please

Hi all,
So HVAC is very new to me as we moved to the US 4 months ago from the UK where it is not required in homes, therefore please bare with me.
Our home has 2 thermostats, 1 upstairs the other downstairs. In the summer they appeared to work fine and independently giving us AC dependant on what temp was set on each of them. No bother.
Turned the system to heat last week and nothing happened, in fact the thermostat upstairs lost all power. Landlord sent out an engineer who advised the system had tripped, he put it back on and did some general 'messing about' with it. We've had issues since, I'll fast forward all his visits and let you know what we are left with.
When we increase the temp on the thermostat downstairs to turn it on, nothing happens downstairs, no vents work so it remains cold however the vents upstairs pump out hot air regardless of what temp the upstairs thermostat is set to. This makes upstairs far too hot, yesterday the upstairs thermostat was set to 69 but continued to rise past 75 because the downstairs thetmostat was on.
Questioned the engineer and he advised this is because we have 2 thermostats but only 1 unit, he said 1 thermostat controls the temp and the other controls the opening of vents!?
He advised the only way to sort this is to close some vents upstairs to force the air to blow out downstairs. He did this and we now get heat downstairs and upstairs when I 'up' the thermostat downstaurs. So both areas are increasing in heat when I really only want heat downstairs (usually because upstairs is already air rising and all that).
My question is, why can not I just get heat downstairs? Why does the downstairs thermostat affect what vents are working upstairs? Had it not worked independently over the summer I wouldn't question him but I know it can work seperately. Thanks in advance for your advice.
Old 11-24-16, 05:02 PM
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You may need to investigate further. Most homes with two thermostats controlling a single system use a motorized zone damper system.

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If this is the case with your home you may have a problem with the zone control board , a damper or some crossed wires.

Another option, though less common, is two thermostats controlling a single system with not damper system. This option can lead to back feed issues and can cause a build up of Ice if one thermostat is placed in the Fan On mode. It is unlikely that you have this option. I would search for the zone control board.

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