On 2022-12-15 11:41:21 +0000, John Rumm said:

> TRVs and a main stat as an interlock will control the total energy
> being used. You can also adjust the temp in each room based on need and
> use with the TRVs. It is important that you don't disable the heating
> in the room with the room stat - since that would also disable the
> interlock. Once the house is up to temperature, you want the heating to
> stop. It can't do that if the main stat is never satisfied because it
> is in a room with the rads off (or with their TRV temp set below that
> of the main stat).

John, is it usual not to have TRVs on some rads - we don't have them on
hallway and bathroom rads, only on all other rooms (apart from one
small utility room).

Our system doen't have a central heating temp stat, only a hot water
tank stat. There is a stat in the ground floor hallway but not
connected to anything. I was thinking of ignoring that and putting in
some kind of wireless control - how easy is that to put in a S-plan
system with an oldish Honeywell programmer?

On 15/12/2022 10:40, AnthonyL wrote:

> Thanks John & alan_m. I think this is finally sinking in.
>
>> A Baxi 105HE is a powerful boiler - it can output 30kW. More the the
>> point its *minimum* output is over 11kW.
>>
>
> Whilst my earlier concerns were first raised in milder weather I was
> expecting the boiler to be modulating in this prolonged cold spell.
> However yesterday I ran some figures with the aid of the Wiser App
> that I now have.
>
> Daily usage is around 4 cu ft gas which comes out (according to me) at

ITYM 4 units (where 1 unit = 100 cu ft), rather than cu ft!

But yup, multiply 4 by 32.15 for an approximation to kWh[1]

[1] http://wiki.diyfaq.org.uk/index.php/Gas_units

> around 126kWh. The app says the boiler (and I assume burner) was on
> for about 15hrs, so 8.4kW which is below the 11kW modulating power you
> mention above. So it has to cycle - got it!!

>> Being a combi, it was probably specified to give decent DHW performance,
>> however from a CH point of view it is probably way oversized.
>>
>
> I believe this is the 3rd boiler, this one being installed in ~2006.
> The first would not have been a combi though it is likely the 2nd was.
> My experience with 3 service engineers is when asked about replacing
> they've all quoted like for like, ie 30kW without going around the
> house which has changed substantially since 1968.

Often the case with heating installers - they don't like doing sums it
seems, and just assume that the person before them did them! It is often
assumptions all the way down.

>> I expect the problem is that you don't have enough heating load - so
>> even with it running at its minimum of 11kW, it rapidly reaches the
>> point as the return temperature rises it can't keep the flow temperature
>> to the limit you have set - so it cycles off - that is its only option
>> at that point.
>>
>> The low flow temp may promote more condensing efficiency, but the system
>> efficiency will be abysmal because of the short cycling - costing more
>> rather than less.
>>
>
> Indeed I have been chasing condensing efficiency. It seems quite a
> steep slope of gain.

It is a steep(ish) slope - but remember it is chasing a marginal gain.
So if a bog standard non condensing modulating boiler can get 75%
overall, and with condensing you can get that to 95% seasonally
adjusted, a 25% improvement in condensing efficiency is 25% of that 20%
gap - so a 5% overall change.

--
Cheers,

John.

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On Thu, 15 Dec 2022 11:52:03 +0000, John Rumm
<see.my.signature@nowhere.null> wrote:

>On 15/12/2022 10:40, AnthonyL wrote:
>
>> Thanks John & alan_m. I think this is finally sinking in.
>>
>>> A Baxi 105HE is a powerful boiler - it can output 30kW. More the the
>>> point its *minimum* output is over 11kW.
>>>
>>
>> Whilst my earlier concerns were first raised in milder weather I was
>> expecting the boiler to be modulating in this prolonged cold spell.
>> However yesterday I ran some figures with the aid of the Wiser App
>> that I now have.
>>
>> Daily usage is around 4 cu ft gas which comes out (according to me) at
>
>ITYM 4 units (where 1 unit = 100 cu ft), rather than cu ft!
>
>But yup, multiply 4 by 32.15 for an approximation to kWh[1]
>
>[1] http://wiki.diyfaq.org.uk/index.php/Gas_units
>

Thankfully my brain was functioning correctly when I set up my
spreadsheet ~ 10yrs ago.

There is some deduction and understanding required, and careful
attention to where the ft3 is written:

https://flic.kr/p/2o62Aaz

However yesterday I was idly thinking that 4 cu ft is only a small box
of gas!

--
AnthonyL

Why ever wait to finish a job before starting the next?

On 15/12/2022 11:50, John Smith wrote:
> On 2022-12-15 11:41:21 +0000, John Rumm said:
>
>> TRVs and a main stat as an interlock will control the total energy
>> being used. You can also adjust the temp in each room based on need
>> and use with the TRVs. It is important that you don't disable the
>> heating in the room with the room stat - since that would also disable
>> the interlock. Once the house is up to temperature, you want the
>> heating to stop. It can't do that if the main stat is never satisfied
>> because it is in a room with the rads off (or with their TRV temp set
>> below that of the main stat).
>
> John, is it usual not to have TRVs on some rads - we don't have them on
> hallway and bathroom rads, only on all other rooms (apart from one small
> utility room).

Yup, that is common and and sometimes "by design". You may also have
some uncontrolled rads (i.e. not even manual adjustment) This often what
you see in the the hall (or other space) shared with the room stat. You
would balance them so that they are among the last to heat to heat up.
The reason they are often setup with a lockshield valve at both ends it
to stop the user from fiddling with them and defeating the interlock
function provided by the stat (i.e. they turn the rad down to "save
money" and as a result the heating never turns off, costing them more).

As TRVs throttle down elsewhere, more flow goes through the (always
open) non controlled rads. That brings the temp in that room up, and
ultimately will turn off the heating using the main stat.

(another reason for always on rads is to make sure there is always a
path for water to flow through the system. Something you need to think
about with S-Plan systems since both valves can be closed)

> Our system doen't have a central heating temp stat, only a hot water
> tank stat. There is a stat in the ground floor hallway but not connected
> to anything.

That basically means the CH runs all the time that the programmer has it
"on". It can cycle on its own internal stat, but will never go properly
off. That may be what you want in the coldest bits of the year, but
quite inefficient during milder parts of the heating season.

> I was thinking of ignoring that and putting in some kind of
> wireless control - how easy is that to put in a S-plan system with an
> oldish Honeywell programmer?

Easy generally. A modern prog stat can in many cases can act as both a
stat and a programmer in one unit (so you either remove the programmer,
or leave it set to permanently "on").

You install the receiver for the stat near the boiler and wire it to the
stat input on that. Then pair the wireless stat with the receiver.

The wireless stat will then let you specify the temperature required at
various times of the day. The simplest will have two temps "normal" an
"set back". The set back one being the baseline it will not let the
property fall below. More sophisticated ones will allow multiple spells
of time at independently selectable temperatures.

So you could program it to say 21 degrees between 7 and 9am, 19 degrees
from 11am to 4pm, then 20 from 6pm to 11pm. With say a setback temp of
15 degrees that it will run all other times.

Posher versions are optimising - they will learn the response of the
house and adjust the time the heating comes on so that it meets your
demand. So with a non optimising stat, if you say 21 degrees from 7 til
9, it will turn the heating on at 7 and run it til 9 - hopefully
reaching and maintaining 21 for the duration. However it will take some
time to reach the set temp. With an optimising stat it might learn that
if you want 21 at 7am, it actually needs to turn the heating on at 6am
to make sure it is 21 by 7am.

--
Cheers,

John.

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\=================================================================/

On 15/12/2022 12:47, AnthonyL wrote:
> On Thu, 15 Dec 2022 11:52:03 +0000, John Rumm
> <see.my.signature@nowhere.null> wrote:
>
>> On 15/12/2022 10:40, AnthonyL wrote:
>>
>>> Thanks John & alan_m. I think this is finally sinking in.
>>>
>>>> A Baxi 105HE is a powerful boiler - it can output 30kW. More the the
>>>> point its *minimum* output is over 11kW.
>>>>
>>>
>>> Whilst my earlier concerns were first raised in milder weather I was
>>> expecting the boiler to be modulating in this prolonged cold spell.
>>> However yesterday I ran some figures with the aid of the Wiser App
>>> that I now have.
>>>
>>> Daily usage is around 4 cu ft gas which comes out (according to me) at
>>
>> ITYM 4 units (where 1 unit = 100 cu ft), rather than cu ft!
>>
>> But yup, multiply 4 by 32.15 for an approximation to kWh[1]
>>
>> [1] http://wiki.diyfaq.org.uk/index.php/Gas_units
>>
>
>
> Thankfully my brain was functioning correctly when I set up my
> spreadsheet ~ 10yrs ago.
>
> There is some deduction and understanding required, and careful
> attention to where the ft3 is written:
>
> https://flic.kr/p/2o62Aaz

Link not working at the mo from here.

> However yesterday I was idly thinking that 4 cu ft is only a small box
> of gas!

Yup, by that measure I could heat this house from farts alone :-)

--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/

On Thu, 15 Dec 2022 16:10:54 +0000, John Rumm
<see.my.signature@nowhere.null> wrote:

>On 15/12/2022 12:47, AnthonyL wrote:
>> On Thu, 15 Dec 2022 11:52:03 +0000, John Rumm
>> <see.my.signature@nowhere.null> wrote:
>>
>>> On 15/12/2022 10:40, AnthonyL wrote:
>>>
>>>> Thanks John & alan_m. I think this is finally sinking in.
>>>>
>>>>> A Baxi 105HE is a powerful boiler - it can output 30kW. More the the
>>>>> point its *minimum* output is over 11kW.
>>>>>
>>>>
>>>> Whilst my earlier concerns were first raised in milder weather I was
>>>> expecting the boiler to be modulating in this prolonged cold spell.
>>>> However yesterday I ran some figures with the aid of the Wiser App
>>>> that I now have.
>>>>
>>>> Daily usage is around 4 cu ft gas which comes out (according to me) at
>>>
>>> ITYM 4 units (where 1 unit = 100 cu ft), rather than cu ft!
>>>
>>> But yup, multiply 4 by 32.15 for an approximation to kWh[1]
>>>
>>> [1] http://wiki.diyfaq.org.uk/index.php/Gas_units
>>>
>>
>>
>> Thankfully my brain was functioning correctly when I set up my
>> spreadsheet ~ 10yrs ago.
>>
>> There is some deduction and understanding required, and careful
>> attention to where the ft3 is written:
>>
>> https://flic.kr/p/2o62Aaz
>
>Link not working at the mo from here.
>

mmm .. I check links that I post from such sites in a Private window
to make sure I'm not in the trap of only working when logged in. In
this case it works in both Firefox and Edge (Win10).

--
AnthonyL

Why ever wait to finish a job before starting the next?

On 15/12/2022 18:10, AnthonyL wrote:
> On Thu, 15 Dec 2022 16:10:54 +0000, John Rumm
> <see.my.signature@nowhere.null> wrote:
>
>> On 15/12/2022 12:47, AnthonyL wrote:
>>> On Thu, 15 Dec 2022 11:52:03 +0000, John Rumm
>>> <see.my.signature@nowhere.null> wrote:
>>>
>>>> On 15/12/2022 10:40, AnthonyL wrote:
>>>>
>>>>> Thanks John & alan_m. I think this is finally sinking in.
>>>>>
>>>>>> A Baxi 105HE is a powerful boiler - it can output 30kW. More the the
>>>>>> point its *minimum* output is over 11kW.
>>>>>>
>>>>>
>>>>> Whilst my earlier concerns were first raised in milder weather I was
>>>>> expecting the boiler to be modulating in this prolonged cold spell.
>>>>> However yesterday I ran some figures with the aid of the Wiser App
>>>>> that I now have.
>>>>>
>>>>> Daily usage is around 4 cu ft gas which comes out (according to me) at
>>>>
>>>> ITYM 4 units (where 1 unit = 100 cu ft), rather than cu ft!
>>>>
>>>> But yup, multiply 4 by 32.15 for an approximation to kWh[1]
>>>>
>>>> [1] http://wiki.diyfaq.org.uk/index.php/Gas_units
>>>>
>>>
>>>
>>> Thankfully my brain was functioning correctly when I set up my
>>> spreadsheet ~ 10yrs ago.
>>>
>>> There is some deduction and understanding required, and careful
>>> attention to where the ft3 is written:
>>>
>>> https://flic.kr/p/2o62Aaz
>>
>> Link not working at the mo from here.
>>
>
> mmm .. I check links that I post from such sites in a Private window
> to make sure I'm not in the trap of only working when logged in. In
> this case it works in both Firefox and Edge (Win10).
>
>

worked for me, then an annoying popup from flickr
blocked out the photo with cookie request information.

On Wed, 14 Dec 2022 13:04:02 +0000, John Rumm
<see.my.signature@nowhere.null> wrote:

>On 13/12/2022 19:46, AnthonyL wrote:
>>
>> We don't have weather compensation on our Baxi 105HE combi. I've
>> recently installed a room thermostat, improved the insulation in the
>> attic (bungalow) and turned off the radiator in the hall completely.
>> I'm trying to learn how the new arrangement performs (11 radiators,
>> one turned off as above, a couple on low) but with a flow temperature
>> of 60 set on the boiler the lounge today has not reached target
>> temperature Thermostat is set for 19 (0630-1030), 17.5 (1030-1630),
>> 19.5 (1630-2230). The Wiser Drayton system has a "smart" mode which
>> means it attempts to reach the 19.5 evening temperature by 1630 rather
>> than start to try to get to it at that time. The current temp is 19
>> and the boiler has been trying to get to the target since 1330.
>>
>> Despite failing to get there the burner still cycles. Approximately:
>>
>> 4 mins to get from 50 to 60 (neons every 10 deg 30 thru 80)
>> 1 min at 60
>> Burner off for 2.5 mins back to 50
>>
>> Pump is operating all the time.
>>
>> Surely the call for heat should keep it running at 60? It's as if the
>> boiler is saying "I'm hot enough now".
>>
>> I can't help feel something is not working as it should. I know its
>> cold but we are using something like 4cu ft /day for heating at a cost
>> of Ł10/day.
>>
>> I'm now going to up the temp a notch to see if we can take an overcoat
>> off before the evening is out.
>>
>> 1968 build, cavity, double glazed, pvc doors, no obvious draughts but
>> two flat roof extensions.
>A Baxi 105HE is a powerful boiler - it can output 30kW. More the the
>point its *minimum* output is over 11kW.
>
>Being a combi, it was probably specified to give decent DHW performance,
>however from a CH point of view it is probably way oversized.
>
>I expect the problem is that you don't have enough heating load - so
>even with it running at its minimum of 11kW, it rapidly reaches the
>point as the return temperature rises it can't keep the flow temperature
>to the limit you have set - so it cycles off - that is its only option
>at that point.
>
>The low flow temp may promote more condensing efficiency, but the system
>efficiency will be abysmal because of the short cycling - costing more
>rather than less.
>
>Set the flow temp to 75, and see how that works.
>
>If that is ok, then chances are the rads were all sized with an
>anticipation of an 11 drop and a high flow temp. The way to "fix" it
>would be to increase the heating load with higher output radiators or
>additional rads. This might mean larger rads, or perhaps double panel
>where there are single, or finned where they are plain etc.
>

The neons on the boiler are every 10 deg so this is a bit rough and
ready but the cycle is now:

T0 Temp 70deg burner turns off
T+3' Pump turns off
T+6' Burner on and fairly quickly up to 70
T+10' Burner off
Cycle repeats

So upping the temp seems to have set a steadier 10min cycle but which
now includes the pump stop/starting. Pressure obviously increases and
is about 2.5 bar.

Is the above an improvement? Do I need to fiddle more?

Additionally, and relating to previous posts and also a recent thread
to another poster, I too have turned off the large hall radiator that
has lockshield valves. The hall is a large unused space. The hall's
current temperature is about 15C. The smaller bathroom radiator also
has lockshield valves and is on and hot. All the 9 other radiators
upstream and downstream are working. I'm not aware and wouldn't know
how to see if there is any zone valves. I'm not sure I've ever
satisfactorily had explained all the pipework coming out of the
(combi) boiler which is at the end the garage/utility room extension,
but I'm fairly sure there is only one out and one return feed running
through the attic.

--
AnthonyL

Why ever wait to finish a job before starting the next?

On 15/12/2022 18:10, AnthonyL wrote:
> On Thu, 15 Dec 2022 16:10:54 +0000, John Rumm
> <see.my.signature@nowhere.null> wrote:

>>> https://flic.kr/p/2o62Aaz
>>
>> Link not working at the mo from here.
>>
>
> mmm .. I check links that I post from such sites in a Private window
> to make sure I'm not in the trap of only working when logged in. In
> this case it works in both Firefox and Edge (Win10).

I think it was a temporary Flickr thing... working now...

--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/