Correct boiler setting

[jpm777]

Hi everyone,

I have a Worcester bosch 19/24cbi boiler and would like to know what you think the best position is for the dial on the front and if there is a difference for winter or summer?

The dial on the front has a dot at the 3 o'clock position, but the manual doesn't explain it at all.

I'm trying to get it to work well with my very sensitive Honeywell DT90e thermostat. It seems to bring the boiler on all the time, even when the house hasn't dropped temperature. When the boiler fires for 1 minute or so, the radiators don't even get warm to maintain the temperature and it seems like a waste of gas and unnecessary stress on the system constantly firing every 5 or 6 minutes. I have experimented with the "on time" for the thermostat but leaving it to run longer makes the radiators hotter but also uses more gas.
I was wondering if the boiler setting should be adjusted in this instance?

Any thoughts much appreciated. Happy Xmas to one and all.

 

[Whitespirit66]

I'm trying to get it to work well with my very sensitive Honeywell DT90e thermostat. It seems to bring the boiler on all the time, even when the house hasn't dropped temperature. When the boiler fires for 1 minute or so, the radiators don't even get warm to maintain the temperature and it seems like a waste of gas and unnecessary stress on the system constantly firing every 5 or 6 minutes.

Your Honeywell stat's not sensitive, it just uses dodgy TPI operation to turn the boiler on and off according to the amount of time that it thinks your boiler needs to maintain the set temp. THis is unlike normal stats that just monitor the actual temp and bring the boiler on and off to maintain the set temp. Typical example of something that sounds clever, but in practice is impractical.

The TPI system is flawed, difficult to explain to customers, supposed to be more energy efficient but wastes it in other ways, creates unnecessary noise and wear and tear and can be annoying if the boiler is audible from rooms in house. TPI makes the boiler fire up for no reason and can sometimes fire the boiler every 4 mins. Exactly the symptoms you describe.

I won't recommend Honeywell any more, as the TPI can't be turned off. However, other manufacturers have stats with similar operation to TPI, but importantly, this can be turned off to allow the stat to work like a normal stat.

I prefer the Drayton Mistat range, as their version of TPI (Chrono Proportional Control) can be switched off on their stats, to allow them to act like a normal stats. This prevents unnecessary boiler firing, etc, etc. I would bin your stat and fit a Drayton.

http://www.draytoncontrols.co.uk/mi-series-mi-stat-room/

 

[mogget]

Is this chrono-proportional control the same as that used in the (discontinued) Digistat 1? IE, varying the set-point slightly over a 20 min cycle, effectively switching the boiler on and off every 20 min? I find it works very well for me, keeps the temperature stable whilst not firing the boiler too often. I have a few Digistat 1's in my spares box as I like them so much.

 

[Whitespirit66]

If it's the older, square '1', then it's not TPI/chron. p.

If it's the newer '+1', then yes, I believe its TPI/CP.

Maybe the Drayton C P works better, or just works better for some people. However, with Honeywell, I have had several people who were very confused why their boiler kept firing when the room was actually over set temp. One asked me to remove the Honeywell, as the boiler was firing every 4 mins and the noise was driving them nuts.

Millions of people must get on with TPI, but for me, it's not worth the aggro. Customers are happy with a stat that they can understand. The new Drayton fulfills that most important criteria.

 

[Dan Robinson]

Installed thousands, never had a problem. Have houses with 7 or 8 TPi stats operating perfectly.

Evo home doesn't use TPi, but it's iwn internal logic. The end result is similar though.

 

[Whitespirit66]

I knew I would set myself up on this one.

I have installed lots too, most without any comeback. However it's the few where the customers didn't like the way they operated or couldn't understand the way they work. To save any aggro, I recommend that customers have the Draytons as they provide the flexibility to have TPI or not. Not selecting TPI means that the new Drayton operates like the old stat that in many cases it replaces.

Properties differ, then add in the fact that there are many different boilers fitted to differing systems, and rightly or wrongly my conclusion is that TPI works better in certain situations.

I've never had someone ask for a stat that works on TPI principles. Customers just want a stat, and for a quiet life, that's what I now give them. A proper stat, not something that seems to be more of a timer that may or may not learn the thermal properties of the building that they are installed in.

 

[Dan Robinson]

To be fair, most people would not know or notice.

 

[mogget]

If it's the older, square '1', then it's not TPI/chron. p.

If it's the newer '+1', then yes, I believe its TPI/CP.

Interesting, yes it's the old square one. But in the summer, with the heating off, it will quite happily click on and off every 20 mins or so all day, if the room is at the right temperature. Maybe it has some early version of proportional control that wasn't advertised. Works well anyhow

I don't like the +1 so much, as it has a smaller display and a clicky dial rather than buttons. I installed them in my parents' house though and they like them, apart from the display being a bit small to read with poor eyesight.

 

[jpm777]

I'm trying to get it to work well with my very sensitive Honeywell DT90e thermostat. It seems to bring the boiler on all the time, even when the house hasn't dropped temperature. When the boiler fires for 1 minute or so, the radiators don't even get warm to maintain the temperature and it seems like a waste of gas and unnecessary stress on the system constantly firing every 5 or 6 minutes.

Your Honeywell stat's not sensitive, it just uses dodgy TPI operation to turn the boiler on and off according to the amount of time that it thinks your boiler needs to maintain the set temp. THis is unlike normal stats that just monitor the actual temp and bring the boiler on and off to maintain the set temp. Typical example of something that sounds clever, but in practice is impractical.

The TPI system is flawed, difficult to explain to customers, supposed to be more energy efficient but wastes it in other ways, creates unnecessary noise and wear and tear and can be annoying if the boiler is audible from rooms in house. TPI makes the boiler fire up for no reason and can sometimes fire the boiler every 4 mins. Exactly the symptoms you describe.

I won't recommend Honeywell any more, as the TPI can't be turned off. However, other manufacturers have stats with similar operation to TPI, but importantly, this can be turned off to allow the stat to work like a normal stat.

I prefer the Drayton Mistat range, as their version of TPI (Chrono Proportional Control) can be switched off on their stats, to allow them to act like a normal stats. This prevents unnecessary boiler firing, etc, etc. I would bin your stat and fit a Drayton.

http://www.draytoncontrols.co.uk/mi-series-mi-stat-room/[/QUOTE]

Hi Whitespirit66,

Interesting you should say that about the Honeywell stat. I've tried experimenting in detail with the settings to no avail. I'm not a technophobe I promise! What frustrates me the most is that my boiler is constantly firing, yet the radiators never get hot. When I change tact and boost the heating when needed to keep a similar temperature, it costs a lot less. I was puzzled that a supposedly energy efficient system was costing me more to run. I guess that the answer is that the stat cannot provide me (whether it is due to the non-condensing boiler or not) with the best solution for my house. It seems a real shame that something that is meant to be so good doesn't appear to work in practise...

Thank you for the link to the Drayton stats. Do you think one that I can turn the TPI off is better than a more basic one? If so do you have any recommendations?

 

[Whitespirit66]

To be fair, most people would not know or notice.

Too true!

 

[Whitespirit66]

If it's the older, square '1', then it's not TPI/chron. p.

If it's the newer '+1', then yes, I believe its TPI/CP.

Interesting, yes it's the old square one. But in the summer, with the heating off, it will quite happily click on and off every 20 mins or so all day, if the room is at the right temperature. Maybe it has some early version of proportional control that wasn't advertised. Works well anyhow

I don't like the +1 so much, as it has a smaller display and a clicky dial rather than buttons. I installed them in my parents' house though and they like them, apart from the display being a bit small to read with poor eyesight.

Doesn't sound right. Does the boiler fire every 20 mins, even in summer? Shouldn't if heating off.

What boiler is it? It's not the hot water pre-heat kicking in regularly?

 

[jpm777]

Thanks everybody for all the replies so far.

I have done a great deal of research into tpi and how it works. I understand the principle perfectly. In principle it seems very good. To use a car analogy, it is easier to maintain speed, rather than slow down and speed up again. This saves wasted fuel. I know this, and this is what I expected from the Honeywell dt90e with its tpi. I also understand from tpi that in the 6cph that is recommended for my boiler type, that it works out what will be required heat wise for that 10 mins in terms of on/off time accordingly. Yet sometimes I turn the boiler off for an hour (modern house) and the temperature does not drop on the stat. Yet the previous hour it would have fired multiple times for no apparent reason with it left on.
The strange thing is it doesn't seem to work in the real world for me and logically from an engineering prospective, I don't understand why....

 

[mogget]

Well it was a Vaillant 418, now it's electric heating till the new year.

No, the boiler doesn't fire in the summer (except for DHW). I turn CH off at the programmer. But being a battery powered thermostat it will still click on and off if the room temperature is near the setpoint. It certainly acts like proportional control, but nowhere is it advertised.

 

[Whitespirit66]

I'm trying to get it to work well with my very sensitive Honeywell DT90e thermostat. It seems to bring the boiler on all the time, even when the house hasn't dropped temperature. When the boiler fires for 1 minute or so, the radiators don't even get warm to maintain the temperature and it seems like a waste of gas and unnecessary stress on the system constantly firing every 5 or 6 minutes.

Your Honeywell stat's not sensitive, it just uses dodgy TPI operation to turn the boiler on and off according to the amount of time that it thinks your boiler needs to maintain the set temp. THis is unlike normal stats that just monitor the actual temp and bring the boiler on and off to maintain the set temp. Typical example of something that sounds clever, but in practice is impractical.

The TPI system is flawed, difficult to explain to customers, supposed to be more energy efficient but wastes it in other ways, creates unnecessary noise and wear and tear and can be annoying if the boiler is audible from rooms in house. TPI makes the boiler fire up for no reason and can sometimes fire the boiler every 4 mins. Exactly the symptoms you describe.

I won't recommend Honeywell any more, as the TPI can't be turned off. However, other manufacturers have stats with similar operation to TPI, but importantly, this can be turned off to allow the stat to work like a normal stat.

I prefer the Drayton Mistat range, as their version of TPI (Chrono Proportional Control) can be switched off on their stats, to allow them to act like a normal stats. This prevents unnecessary boiler firing, etc, etc. I would bin your stat and fit a Drayton.

http://www.draytoncontrols.co.uk/mi-series-mi-stat-room/[/QUOTE]

Hi Whitespirit66,

Interesting you should say that about the Honeywell stat. I've tried experimenting in detail with the settings to no avail. I'm not a technophobe I promise! What frustrates me the most is that my boiler is constantly firing, yet the radiators never get hot. When I change tact and boost the heating when needed to keep a similar temperature, it costs a lot less. I was puzzled that a supposedly energy efficient system was costing me more to run. I guess that the answer is that the stat cannot provide me (whether it is due to the non-condensing boiler or not) with the best solution for my house. It seems a real shame that something that is meant to be so good doesn't appear to work in practise...

Thank you for the link to the Drayton stats. Do you think one that I can turn the TPI off is better than a more basic one? If so do you have any recommendations?

The problems that you are experiencing are exactly the same as I have found with this operating system.

If you need a wired stat, the Danfoss RET-B (not the RF version) has selectable chrono p. Or if wireless, the Drayton is good and is the latest technology but operating as a proper stat. These digital stats will provide more accurate control than the traditional dial stats.

http://www.heatingcontrolsonline.co...nfoss-randall-retb-room-thermostat-p-243.html

Hope this helps.

 

[Steelmasons]

TPI in conjunction with an SE boiler (non condensing)? , would be checking the hex for corrosion (back end rot).

Tut tut.