Danfoss TP5000Si Thermostat - Chrono Proportional Control

[infrequentuser]

I've just upgraded my stat from a Danfoss RMT230 to a Danfoss TP5000Si.

One of the facilities offered by the new stat is Danfoss' "Chrono Proportional Control" (CPC).

I'm unclear as to the best setting (number of cycles per hour) to use for the CPC.

The stat offers a choice of 3, 6, 9 or 12.

I can't find any documentation (Danfoss originated or otherwise) that thoroughly discusses the choice of setting and the relevant criteria. Certain 'mentions' on the Danfoss site seem to indicate that a setting of 3 or 6 is typical for radiator systems. The Danfoss doc for the RET B stat suggests a setting of 3 for 'Underfloor' heating and 6 for 'Radiator' systems. The Danfoss doc for the TP7000 suggests a setting of 3 for high thermal inertia systems (eg floor standing cast iron boilers) and 6 for low thermal inertia systems (eg low water content and combi boilers). The Danfoss doc for the TP5000Si is pretty much silent but there is a default of 3 on the stat whilst other docs on the Danfoss website indicate a default of 6 ????

My boiler is a fan assisted Glow Worm Ultimate (cast iron).

Has anyone any advice on this issue ? Thanks.

 

[infrequentuser]

Slight correction :

The default on the battery version of the TP5000Si is 6 cycles per hour not the 3 cycles per hour I quote above. However, the default for the mains powered version seems to be 3 cycles per hour. Difficult for me to understand why these differ.

 

[tamz]

Probably better setting it to 3 as your boiler, being cast iron, is slow to react.

I hope you are not expecting this to save you money.

 

[DP]

Tamz, why would a programmable roomstat replacing a standard stat, if used as intended not save money.

My belief is that any thing that controls the boiler firing better is money in pocket but you think different. Can you say why?

 

[tamz]

My belief is that any thing that controls the boiler firing better is money in pocket but you think different. Can you say why?

I am not a great believer that a programmable stat will deliver much of a saving over a stat and clock especially on an older system with a cast boiler or a badly insulated house. Yes they are faster reacting and the CPC bit tries to smooth things out (how well?) but why would anyone other than your old mother need a setback temp?

It is 17 deg in my house now (and will probably fall to 16 or so later) and the heating has been off for about an hour and a half but if i were to leave the programmable as it was factory set at 18 (as most people do) the heating would be back on and i don't need it to be, i'm usually out. So the boiler would be keeping an empty house warm. I also have the windows open as it is a nice day and does the smart stat know this?
My house is up to temp in around half an hour so i don't need it to keep things ticking along. I've got mine set back to 10 deg to keep it off during the day so effectively it is working just like a stat and clock so where are the savings?
It is the same with the weather comps, telling you it is not cold. If you feel cold/hot put the heating on/off regardless of what your box on the wall says. People live far different lifesyles and are hot or cold for more reasons than a smart box will ever figure out.

 

[DP]

Fair point.

I use the 6 settings and have seen my bills reduced. My good lady complained that the house was cold (initially) but now is used to programmer managing the ambient temperature.

 

[infrequentuser]

Thanks for the advice/comment.

Cost is not a significant motivation - I just think the programmable stat offers me more flexible control.

In terms of the CPC setting, are we all agreed that 3 cycles per hour looks the best bet ? Does anyone have a contrary view ?

Thanks

 

[infrequentuser]

Any other views ? Does everybody feel 3 cycles per hour is the best setting for a 'cast iron' boiler radiator system ?

Thanks again.