Is it possible to use both a heat pump and boiler in the same system?

If it is what are the disadvantages?

On Wed, 29 Mar 2023 10:37:54 +0100, Graham Harrison wrote:

> Is it possible to use both a heat pump and boiler in the same system?
>
> If it is what are the disadvantages?

I have an electric boiler for DHW and anti legionella sterilisation,
because the heat pump can't heat DHW hot enough and the radiator system at
the samw time.

On 29/03/2023 10:37, Graham Harrison wrote:
> Is it possible to use both a heat pump and boiler in the same system?
>
> If it is what are the disadvantages?

https://www.theheatinghub.co.uk/articles/hybrid-heat-pumps

Graham Harrison <edward.harrisom.one@btinternet.com> wrote:
> Is it possible to use both a heat pump and boiler in the same system?

Yes. Grant in particular (being an oil boiler mfr really) have support for
this.

> If it is what are the disadvantages?

Plus:
Resilience of supply (pricing arbitrage, power cuts)
Possibly lower running costs if you're in very sub zero temps (Scottish
mountains etc)

Minuses:
Maintaining two heat sources
Complexity
Installation cost
Space
CO2 emissions

Basically it could make sense if you have a huge listed stone farmhouse with
crap insulation, but it's overkill for the average suburban house.

Theo

On 29/03/2023 11:47, Theo wrote:
> Graham Harrison <edward.harrisom.one@btinternet.com> wrote:
>> Is it possible to use both a heat pump and boiler in the same system?
>
> Yes. Grant in particular (being an oil boiler mfr really) have support for
> this.
>
>> If it is what are the disadvantages?
>
> Plus:
> Resilience of supply (pricing arbitrage, power cuts)
> Possibly lower running costs if you're in very sub zero temps (Scottish
> mountains etc)
>
> Minuses:
> Maintaining two heat sources
> Complexity
> Installation cost
> Space
> CO2 emissions
>
>
> Basically it could make sense if you have a huge listed stone farmhouse with
> crap insulation, but it's overkill for the average suburban house.

I've seen a few videos on hybrid boiler and heat pump systems. They have
been in large properties such as hotels etc. where it's been the
solution for piece-meal renovation. Large amounts of hot water being
required in short time periods and where rooms are being renovated over
a long time scale and so radiators in many rooms may not be ideal for a
lower flow temperature.

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

On 29/03/2023 10:46, Smolley wrote:
> On Wed, 29 Mar 2023 10:37:54 +0100, Graham Harrison wrote:
>
>> Is it possible to use both a heat pump and boiler in the same system?
>>
>> If it is what are the disadvantages?
>
> I have an electric boiler for DHW and anti legionella sterilisation,
> because the heat pump can't heat DHW hot enough and the radiator system at
> the samw time.

Doesn't your heat pump system have the ability to just heat the DHW
above 60C say once a month?

Even at 50˚C 90% of legionella dies in between 80 and 124 minutes
depending on the strain

Smolley <s@home.net> wrote:
> On Wed, 29 Mar 2023 10:37:54 +0100, Graham Harrison wrote:
>
> > Is it possible to use both a heat pump and boiler in the same system?
> >
> > If it is what are the disadvantages?
>
> I have an electric boiler for DHW and anti legionella sterilisation,
> because the heat pump can't heat DHW hot enough and the radiator system at
> the samw time.

Electric boiler (separate box on the wall) or immersion heater (coil in the
hot water tank)? Every hot water tank has an immersion heater (they are
cheap), but they don't do space heating.

You can have an inline immersion in a buffer tank too, which would do space
heating but an 'electric boiler' is typically much bigger (6-10kW+). People
generally only fit those as a cheap install solution (why if you're paying
for a heat pump, as the electric boiler has horrendous running costs) or as
a backup (in a care home or somewhere the heating absolutely cannot fail).

Theo

On Wed, 29 Mar 2023 13:28:59 +0100, Fredxx wrote:

> On 29/03/2023 10:46, Smolley wrote:
>> On Wed, 29 Mar 2023 10:37:54 +0100, Graham Harrison wrote:
>>
>>> Is it possible to use both a heat pump and boiler in the same system?
>>>
>>> If it is what are the disadvantages?
>>
>> I have an electric boiler for DHW and anti legionella sterilisation,
>> because the heat pump can't heat DHW hot enough and the radiator system
>> at the samw time.
>
> Doesn't your heat pump system have the ability to just heat the DHW
> above 60C say once a month?
>
> Even at 50˚C 90% of legionella dies in between 80 and 124 minutes
> depending on the strain

I can manually divert heat pump flow to DHW coils, but water temp doesn't
exceed 45C and of course there is no sterilisation cycle.

On 29/03/2023 13:47, Smolley wrote:
> On Wed, 29 Mar 2023 13:28:59 +0100, Fredxx wrote:
>
>> On 29/03/2023 10:46, Smolley wrote:
>>> On Wed, 29 Mar 2023 10:37:54 +0100, Graham Harrison wrote:
>>>
>>>> Is it possible to use both a heat pump and boiler in the same system?
>>>>
>>>> If it is what are the disadvantages?
>>>
>>> I have an electric boiler for DHW and anti legionella sterilisation,
>>> because the heat pump can't heat DHW hot enough and the radiator system
>>> at the samw time.
>>
>> Doesn't your heat pump system have the ability to just heat the DHW
>> above 60C say once a month?
>>
>> Even at 50˚C 90% of legionella dies in between 80 and 124 minutes
>> depending on the strain
>
> I can manually divert heat pump flow to DHW coils, but water temp doesn't
> exceed 45C and of course there is no sterilisation cycle.

That's a shame, 50C would be the absolute minimum. 60C is the
recommended temperature.

In message <u01e5b$a523$1@dont-email.me>, Fredxx <fredxx@spam.uk> writes
>On 29/03/2023 13:47, Smolley wrote:
>> On Wed, 29 Mar 2023 13:28:59 +0100, Fredxx wrote:
>>
>>> On 29/03/2023 10:46, Smolley wrote:
>>>> On Wed, 29 Mar 2023 10:37:54 +0100, Graham Harrison wrote:
>>>>
>>>>> Is it possible to use both a heat pump and boiler in the same system?
>>>>>
>>>>> If it is what are the disadvantages?
>>>>
>>>> I have an electric boiler for DHW and anti legionella sterilisation,
>>>> because the heat pump can't heat DHW hot enough and the radiator system
>>>> at the samw time.
>>>
>>> Doesn't your heat pump system have the ability to just heat the DHW
>>> above 60C say once a month?
>>>
>>> Even at 500 >>> depending on the strain
>> I can manually divert heat pump flow to DHW coils, but water temp
>>doesn't
>> exceed 45C and of course there is no sterilisation cycle.
>
>That's a shame, 50C would be the absolute minimum. 60C is the
>recommended temperature.

I haven't done it but wonder if our thermal store gets round this issue.
Mind, directly heated mains water, target 45C is going to make an
uncomfortable bath:-)

--
Tim Lamb

On 29/03/2023i 10:37, Graham Harrison wrote:
> Is it possible to use both a heat pump and boiler in the same system?
>
> If it is what are the disadvantages?

Personally, I would go for separate air source AC style heat pumps, then
you get the benefit of being able to have cooling in the summer, but
with the disadvantage you still need your original system for hot water...

.... unless you add solar panels or solar water water heating....

Dave

David Wade <g4ugm@dave.invalid> wrote:
> On 29/03/2023i 10:37, Graham Harrison wrote:
> > Is it possible to use both a heat pump and boiler in the same system?
> >
> > If it is what are the disadvantages?
>
> Personally, I would go for separate air source AC style heat pumps, then
> you get the benefit of being able to have cooling in the summer, but
> with the disadvantage you still need your original system for hot water...
>
> ... unless you add solar panels or solar water water heating....

Solar hot water might cover 60-70% of the year, but the piping and
maintenance is a faff. PV would be easier but need more panels.

If you want cooling, an air to water HP will do that too - you just need to
install fan coils rather than / in addition to radiators. Radiators are
useful for heating as they're mostly silent, which forced air (fan coil or
air2air HP) isn't.

Just depends on what your priorities are really...

Theo

On Wed, 29 Mar 2023 16:42:19 +0100, David Wade wrote:

> On 29/03/2023i 10:37, Graham Harrison wrote:
>> Is it possible to use both a heat pump and boiler in the same system?
>>
>> If it is what are the disadvantages?
>
> Personally, I would go for separate air source AC style heat pumps, then
> you get the benefit of being able to have cooling in the summer, but
> with the disadvantage you still need your original system for hot
> water...
>
> ... unless you add solar panels or solar water water heating....
>
> Dave

https://ibb.co/bQLLzPp

On 29/03/2023 10:37, Graham Harrison wrote:
> Is it possible to use both a heat pump and boiler in the same system?
>
> If it is what are the disadvantages?

If the boiler is mains gas then you will be stung for
gas standing charges as well as electricity.