which thermostat to purchase

jim_51

I have a viessmann vitogas 100 boiler with copper fin tubed baseboard. I am looking to replace my thermostat with a digital set back. What are your recommendations?

Thanks much.

Jim

Mark Eatherton

Why programmable?

I am of the opinion that if you have an outdoor reset, you should not be doing a deep set back, because the boiler reset control, and the programmable thermostat do not speak the same language. If they do speak the same language, then your comfort won't suffer too badly. If you DON'T have an outdoor reset controller, you can do shallow set backs, but if the home cools down significantly during set back, it is an indication that you need to spend some money on basic energy conservation, like insulation, caulking, weather striping etc. A good dwelling won't lose much temperature during set back conditions.



I had a nice Honeywell programmable set back thermostat with A.I.R.S. (active intelligent recovery system) which did not work, because the thermostat always assumed maximum output from the heat source, when in reality, the water supply temp was being controlled by the boilers on board computer. It finally got to the point that the programmable stat would only set back for one hour, so it could hit its wake up target.



Virtually useless.



I generally recommend to people that if they want a cooler sleeping environment and it is separately zoned, keep just those rooms turned down, and keep the other zones at their normal settings.



Of course, the exception to this rule would be if the home is completely unoccupied for a long (week or better) period to time. And then, you will want someone to go in and turn the stats back up prior to your arrival, otherwise you will have to wait for the mass in the home to recover, which could take days.



HTH



ME

Jean-David Beyer

If only I had read M.E.'s post 5 years or so ago ;-)

when I bought my fancy thermostat. It has 4 temperature settings for each of the 7 days of the week. Probably just the thing for a forced hot air system. My house did not have outdoor reset then. But even so, it was not much use because the downstairs is radiant heated on grade slab. So if I set back the temperature at night, it never gets down to the setback temperature, and then I have to turn the heat back up at 3AM to recover a degree or so. House too well insulated for that, and the thermal mass of the slab too high. I now have it programmed to set back one degree, and this mainly so it is heating when I get up. And I do not know how that will work with my new boiler that does have outdoor reset. It might be more use upstairs, where I have a similar thermostat and fin tube baseboard heat as a (now) separate zone.



I will not pull out the fancy thermostat though, because it has a nice vacation setback feature. I can tell it how many days to hold the setback (up to 255 days), and then what part of the day to resume the normal program. So I can set it to be 62F while I am away and go back to 67F the morning when I will be back in the evening.

JK_3

I like the

I like the Honeywell vision pro 8000 for these types of applications. (except if there is radiant involved) because with or without outdoor reset the cooler nite time temps would have the boiler running at higher temps and not running at all for several hours will usuallly result in savings. Baseboard systems recover pretty quickly. And if the house is well insullated the the outdoor reset will keep the boiler running efficenly to make up only a couple of degrees. I agree with not using set backs for short periods of time .

heatboy_30

Which Control?

Depending on the Viessmann control being used, you can utilize the setback built into the control. This lowers water temps, which will in turn, lower structure temperatures. Makes much more sense than any set back thermostat that shuts the system down and allows the mass to go cold.

jim_51

Control for Vitogas

The unit has a vitotrol 200 control with outdoor reset along with 2 zones and baseboard fin tubed copper.



Thanks for the help.