If a heating boiler is run all night and the thermostatic radiator
valves are turned down, then there might be very little flow through the
pipes when the valves start to shut off.

This is assuming no bypass circuit to maintain flow has been fitted, or
it too has been almost closed.

Would this cause damage or undue wear to the heating pump?

(I am asking about a regular combi boiler, such as a Baxi 630.)

On 30/11/2023 20:18, Pamela wrote:
> If a heating boiler is run all night and the thermostatic radiator
> valves are turned down, then there might be very little flow through the
> pipes when the valves start to shut off.
>
> This is assuming no bypass circuit to maintain flow has been fitted, or
> it too has been almost closed.
>
> Would this cause damage or undue wear to the heating pump?
>
> (I am asking about a regular combi boiler, such as a Baxi 630.)

If no bypass has been fitted there is usually a radiator on the system
that shouldn't be shut off, maybe a towel rail or a bathroom radiator
without a TVR.

If a room stat is being used the radiator in that room should not have a
TVR. The TVR may close down the radiator before the thermostat
temperature is reached and the boiler will be continuously be getting
the demand for heat.

While there may not be a dedicated bypass circuit the system may have a
radiator or two working as a bypass.

The pump in a modern combi boiler may/will be working in proportional
pressure control mode and adjust to TVRs shutting down.

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 30/11/2023 20:18, Pamela wrote:
> If a heating boiler is run all night and the thermostatic radiator
> valves are turned down, then there might be very little flow through the
> pipes when the valves start to shut off.
>
> This is assuming no bypass circuit to maintain flow has been fitted, or
> it too has been almost closed.
>
> Would this cause damage or undue wear to the heating pump?
>
> (I am asking about a regular combi boiler, such as a Baxi 630.)

Much more likely that the flow becomes too low and the boiler shuts down
and flags up a fault.

On 30/11/2023 20:55, alan_m wrote:
> On 30/11/2023 20:18, Pamela wrote:
>> If a heating boiler is run all night and the thermostatic radiator
>> valves are turned down, then there might be very little flow through the
>> pipes when the valves start to shut off.
>>
>> This is assuming no bypass circuit to maintain flow has been fitted, or
>> it too has been almost closed.
>>
>> Would this cause damage or undue wear to the heating pump?
>>
>> (I am asking about a regular combi boiler, such as a Baxi 630.)
>
> If no bypass has been fitted there is usually a radiator on the system
> that shouldn't be shut off, maybe a towel rail or a bathroom radiator
> without a TVR.
>
> If a room stat is being used the radiator in that room should not have a
> TVR. The TVR may close down the radiator before the thermostat
> temperature is reached and the boiler will be continuously be getting
> the demand for heat.
>
> While there may not be a dedicated bypass circuit the system may have a
> radiator or two working as a bypass.
>
> The pump in a modern combi boiler may/will be working in proportional
> pressure control mode and adjust to TVRs shutting down.
>
TVR is a sports car.

restricted flow tends to lead to short cycling on the boiler, or an
overheat condition within it

--
Gun Control: The law that ensures that only criminals have guns.

On 20:55 30 Nov 2023, alan_m said:

> On 30/11/2023 20:18, Pamela wrote:
>> If a heating boiler is run all night and the thermostatic radiator
>> valves are turned down, then there might be very little flow through the
>> pipes when the valves start to shut off.
>>
>> This is assuming no bypass circuit to maintain flow has been fitted, or
>> it too has been almost closed.
>>
>> Would this cause damage or undue wear to the heating pump?
>>
>> (I am asking about a regular combi boiler, such as a Baxi 630.)
>
> If no bypass has been fitted there is usually a radiator on the system
> that shouldn't be shut off, maybe a towel rail or a bathroom radiator
> without a TVR.
>
> If a room stat is being used the radiator in that room should not have a
> TVR. The TVR may close down the radiator before the thermostat
> temperature is reached and the boiler will be continuously be getting
> the demand for heat.
>
> While there may not be a dedicated bypass circuit the system may have a
> radiator or two working as a bypass.
>
> The pump in a modern combi boiler may/will be working in proportional
> pressure control mode and adjust to TVRs shutting down.

There's a bypass in the form of a heated towel radiator in the bathroom but
it has to be almost left closed or the room gets unbearably hot. (The
radiator goes from floor to ceiling and all the walls are isolated to allow
tiles to lie squarely.)

My old boiler would stop and show a fault when the TRVs shut down. I was
wondering if the pump in a modern boiler will slow down to almost no
rotation when presented with very low flow.

Perhaps the safest thing to do is lower the heating thermostat on the
boiler so the rooms don't get too warm overnight and shut the TRVs.

On 23:02 30 Nov 2023, SteveW said:
> On 30/11/2023 20:18, Pamela wrote:
>>
>> If a heating boiler is run all night and the thermostatic radiator
>> valves are turned down, then there might be very little flow through
>> the pipes when the valves start to shut off.
>>
>> This is assuming no bypass circuit to maintain flow has been fitted,
>> or it too has been almost closed.
>>
>> Would this cause damage or undue wear to the heating pump?
>>
>> (I am asking about a regular combi boiler, such as a Baxi 630.)
>
> Much more likely that the flow becomes too low and the boiler shuts
> down and flags up a fault.

I used to get a boiler fault on my previous boiler (an old Ideal Isar
from decades ago) when the TRVs shut off. It seems the pipework isn't a
large loop with the radiators spurring off it.

On 30/11/2023 20:18, Pamela wrote:
> If a heating boiler is run all night and the thermostatic radiator
> valves are turned down, then there might be very little flow through the
> pipes when the valves start to shut off.
>
> This is assuming no bypass circuit to maintain flow has been fitted, or
> it too has been almost closed.
>
> Would this cause damage or undue wear to the heating pump?
>
> (I am asking about a regular combi boiler, such as a Baxi 630.)

Well to quote from the manual:

"5.2.4 Bypass
The boiler utilises the primary side of the DHW plate heat exchanger as
an automatic integral bypass."

However as a general rule, you will not damage a boiler with short term
use like that... it will either short cycle on it's internal stat, or if
flow is completely occluded, trip out with a fault code.

In a more general sense, long term use will increase the wear rate on
the parts since there is far more stopping and starting.

There should also be some form of interlock that prevents the boiler
running when the house is already up to temperature. This is typically a
room stat in a room with a fixed output radiator.

--
Cheers,

John.

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| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/

On 01/12/2023 10:53, Pamela wrote:

>
> Perhaps the safest thing to do is lower the heating thermostat on the
> boiler so the rooms don't get too warm overnight and shut the TRVs.

Possibly the worst thing you could do is lower the flow temperature at
the boiler (boiler thermostat??) as this could/will cause short cycling.
Short cycling is not good for the longevity of the boiler.

I don't know how sophisticated your controls are but a programmable room
thermostat may be a solution. A programmable room thermostat allows
different temperatures for different periods of the days to be set. For
instance with mine I set a low target temperature during the period 11pm
to 6:30am then a couple of day/evening temperatures depending on the
time of day.

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 30/11/2023 20:55, alan_m wrote:
> On 30/11/2023 20:18, Pamela wrote:
>> If a heating boiler is run all night and the thermostatic radiator
>> valves are turned down, then there might be very little flow through the
>> pipes when the valves start to shut off.
>>
>> This is assuming no bypass circuit to maintain flow has been fitted, or
>> it too has been almost closed.
>>
>> Would this cause damage or undue wear to the heating pump?
>>
>> (I am asking about a regular combi boiler, such as a Baxi 630.)
>
> If no bypass has been fitted there is usually a radiator on the system
> that shouldn't be shut off, maybe a towel rail or a bathroom radiator
> without a TVR.

That's rather slack. A heated towel rail might be turned off. It can't
be assumed that the user knows that something has to be left on.

--
Max Demian

On 01/12/2023 11:26, alan_m wrote:
> On 01/12/2023 10:53, Pamela wrote:

>> Perhaps the safest thing to do is lower the heating thermostat on the
>> boiler so the rooms don't get too warm overnight and shut the TRVs.
>
> Possibly the worst thing you could do is lower the flow temperature at
> the boiler (boiler thermostat??) as this could/will cause short cycling.
> Short cycling is not good for the longevity of the boiler.

Better for economy as condensation is more efficient. That's what I do
as the TRVs are fiddly and noisy.

--
Max Demian

On 01/12/2023 12:40, Max Demian wrote:
> On 01/12/2023 11:26, alan_m wrote:
>> On 01/12/2023 10:53, Pamela wrote:
>
>>> Perhaps the safest thing to do is lower the heating thermostat on the
>>> boiler so the rooms don't get too warm overnight and shut the TRVs.
>>
>> Possibly the worst thing you could do is lower the flow temperature at
>> the boiler (boiler thermostat??) as this could/will cause short
>> cycling. Short cycling is not good for the longevity of the boiler.
>
> Better for economy as condensation is more efficient. That's what I do
> as the TRVs are fiddly and noisy.
>

It only better if the boiler can modulate down far enough to keep the
flow dialled in (lower) temperature. If the boiler cannot not modulate
down far enough you just get short cycling. Many UK boilers are
oversized for the (CH) system and cannot sustain a efficient burn.

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 01/12/2023 12:38, Max Demian wrote:
> On 30/11/2023 20:55, alan_m wrote:
>> On 30/11/2023 20:18, Pamela wrote:
>>> If a heating boiler is run all night and the thermostatic radiator
>>> valves are turned down, then there might be very little flow through the
>>> pipes when the valves start to shut off.
>>>
>>> This is assuming no bypass circuit to maintain flow has been fitted, or
>>> it too has been almost closed.
>>>
>>> Would this cause damage or undue wear to the heating pump?
>>>
>>> (I am asking about a regular combi boiler, such as a Baxi 630.)
>>
>> If no bypass has been fitted there is usually a radiator on the system
>> that shouldn't be shut off, maybe a towel rail or a bathroom radiator
>> without a TVR.
>
> That's rather slack. A heated towel rail might be turned off. It can't
> be assumed that the user knows that something has to be left on.
>

It may be "slack" but it is/was a common practice.

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 01/12/2023 12:38, Max Demian wrote:
> On 30/11/2023 20:55, alan_m wrote:
>> On 30/11/2023 20:18, Pamela wrote:
>>> If a heating boiler is run all night and the thermostatic radiator
>>> valves are turned down, then there might be very little flow through the
>>> pipes when the valves start to shut off.
>>>
>>> This is assuming no bypass circuit to maintain flow has been fitted, or
>>> it too has been almost closed.
>>>
>>> Would this cause damage or undue wear to the heating pump?
>>>
>>> (I am asking about a regular combi boiler, such as a Baxi 630.)
>>
>> If no bypass has been fitted there is usually a radiator on the system
>> that shouldn't be shut off, maybe a towel rail or a bathroom radiator
>> without a TVR.
>
> That's rather slack. A heated towel rail might be turned off. It can't
> be assumed that the user knows that something has to be left on.

It's no longer accepted practice. A system must now be fitted with a
bypass valve.

In message <ukcloq$1sh83$1@dont-email.me>, Fredxx <fredxx@spam.invalid>
writes
>On 01/12/2023 12:38, Max Demian wrote:
>> On 30/11/2023 20:55, alan_m wrote:
>>> On 30/11/2023 20:18, Pamela wrote:
>>>> If a heating boiler is run all night and the thermostatic radiator
>>>> valves are turned down, then there might be very little flow through the
>>>> pipes when the valves start to shut off.
>>>>
>>>> This is assuming no bypass circuit to maintain flow has been fitted, or
>>>> it too has been almost closed.
>>>>
>>>> Would this cause damage or undue wear to the heating pump?
>>>>
>>>> (I am asking about a regular combi boiler, such as a Baxi 630.)
>>>
>>> If no bypass has been fitted there is usually a radiator on the
>>>system that shouldn't be shut off, maybe a towel rail or a bathroom
>>>radiator without a TVR.
>> That's rather slack. A heated towel rail might be turned off. It
>>can't be assumed that the user knows that something has to be left on.
>
>It's no longer accepted practice. A system must now be fitted with a
>bypass valve.

Operated by rising system pressure? One was fitted by my plumbers. Sadly
the circuit arrangement is such that the pressure then drops below the
hysteresis point and the valve re-closes leading to system hammer. On
the *to do* list when I next do a drain down and have discovered a
solution!
Yes. I do have a suitable, charged, pressure vessel.
--
Tim Lamb

On 01/12/2023 12:38, Max Demian wrote:
> On 30/11/2023 20:55, alan_m wrote:
>> On 30/11/2023 20:18, Pamela wrote:
>>> If a heating boiler is run all night and the thermostatic radiator
>>> valves are turned down, then there might be very little flow through the
>>> pipes when the valves start to shut off.
>>>
>>> This is assuming no bypass circuit to maintain flow has been fitted, or
>>> it too has been almost closed.
>>>
>>> Would this cause damage or undue wear to the heating pump?
>>>
>>> (I am asking about a regular combi boiler, such as a Baxi 630.)
>>
>> If no bypass has been fitted there is usually a radiator on the system
>> that shouldn't be shut off, maybe a towel rail or a bathroom radiator
>> without a TVR.
>
> That's rather slack. A heated towel rail might be turned off. It can't
> be assumed that the user knows that something has to be left on.

Which is why you install that radiator without user adjustable valves on
it.

However many modern boilers include an internal bypass these days.

--
Cheers,

John.

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|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/

On 01/12/2023 10:54, Pamela wrote:
> On 23:02 30 Nov 2023, SteveW said:
>> On 30/11/2023 20:18, Pamela wrote:
>>>
>>> If a heating boiler is run all night and the thermostatic radiator
>>> valves are turned down, then there might be very little flow through
>>> the pipes when the valves start to shut off.
>>>
>>> This is assuming no bypass circuit to maintain flow has been fitted,
>>> or it too has been almost closed.
>>>
>>> Would this cause damage or undue wear to the heating pump?
>>>
>>> (I am asking about a regular combi boiler, such as a Baxi 630.)
>>
>> Much more likely that the flow becomes too low and the boiler shuts
>> down and flags up a fault.
>
> I used to get a boiler fault on my previous boiler (an old Ideal Isar
> from decades ago) when the TRVs shut off. It seems the pipework isn't a
> large loop with the radiators spurring off it.

It is a loop of sorts, but with the radiators (in parallel) forming a
part of it. So if you interrupt the flow on all rads you no longer have
a loop :-)

--
Cheers,

John.

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