Question on thermostats

bink

Do thermostats have to be matched to the zone valves. My contractor changed the thermostat from a round Honeywell Mercury type to a new digital model 3000. With both thermostats old and new the thermostat cycled quite a lot and is turning on and off in short intervals like it is trying to get a very small temperature gain less than .5 degrees I estimate. Because the boiler is controlled by the thermostat I am getting these short boiler runs which has me concerned.
Is it possible to get a new thermostat with adjustment to increase the temp difference so it stays on longer and cycles less .Any advice is appreciated.

KC_Jones

Look at the manual and see if there is a Cylces Per Hour (CPH) setting OR a setting for system type. You want this set for hot water heat or I THINK 2 CPH. Most of them come set from the factory for forced hot air which I think is 6 CPH meaning it will try and run the system 6 times per hour roughly. The installer (if he isn't an idiot) should have known this and set it for you to be honest.

bink

Thanks KC on the inside of the thermostat there is only a two position setting (gas or oil) or (electric or heat pump) he set it to gas or oil. There is no setting for cycles per hour.
The manual also does not discuss Cohen.

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Manual does not discuss cph

KC_Jones

What brand is it?

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Honeywell model 3000 pro. I just called the support line at Honeywell they said because it is a pro model the changes have to be made by the contractor. I saw that holding the two buttons up and down buttons simultaneously this takes you to a setting menu but without the instructions I cannot set it.

KC_Jones

Try this, page 8
https://www.forwardthinking.honeywell.com/related_links/thermostats/pro_3000/install/69_1846.pdf

Jamie Hall

There may be a cycles per hour setting for that thermostat, but as you have found out it's not intended for the homeowner and, if there is, it's not in the User's Manual. It does sound as though that that is your problem.

From the descriptions I find of that thermostat, it very much looks as though it is meant for heat pumps and forced hot air systems of various kinds -- so it may not be usable.

What was the matter with the old reliable round Honeywell, that you had to replace it?

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I thought he was replacing the old to prevent the short cycling but this did not fix it. I am trying to believe they are the professionals but am starting to question this.
Thanks for the reply. I think I need a thermostat that the cph can be set to eliminate the short burner running.

Dave H_2

Bink,
There are other upgrades than the thermostat to help your heating system become more efficient. Controlling the cycles per hour is a way, but it may greatly affect your comfort meaning that it can get cold in your home before the thermostat can even think of turning on the system because the number of cycles has already been reached.

Consider Outdoor Reset control and/ or variable speed circulators that affect the boiler directly to add the economy of operation WITHOUT sacrificing comfort.

Dave H.

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Thanks Jamie for the link to the manual. Dave H thanks I agree I need to consider the cph effect on comfort.

bink

KC the link to the manual you set shows how to check the cph mine is set at 5 so I will discuss with contractor Monday.

Aaron_in_Maine

Some digital tstats also have a temperature differential. Most are set to .5 degrees from the factory. I have Braeburn digital tstats that I changed the diff to 1 degree. My short cycling has been helped dramatically.