Thermostat Sensors - Air Source Heat Pumps

greenfalco

Hello, I'm a newbie to Smart Heating and getting confused very quickly.

I'm buying a new home (a few months off being built so I have time to research) which comes with an air source heat pump installed. The ground floor will have underfloor heating and the upstairs will have radiators (and a hot water tank). I would like to install a smart thermostat with a couple of thermostat sensors so I can control the temperatures at various times in various locations of the house.

What I don't understand is how the thermostat sensors control specific areas if the air source heat pump heats the whole house. I assume the heating will be split into 2 zones (downstairs and upstairs). How does the thermostat sensor heat a specific area say master bedroom (for example) without the air source heat pump heating the entire upstairs? Same goes for a specific area downstairs like the living room.

Would the entire home need to be split up into several zones for this to really work? If so, can this be done retrospectively or does it need to be done during installation?


Many thanks

GF

QrizB

Without more details of the system you've got in mind it's hard to say.

One method is to fit smart valves to every radiator, then control those to achieve the temperature profile you want. That doesn't sound to be quite what you're looking at but it might be.

Astria

You have 2 options which I think you have already thought about: one is to create 2 actually different zones with different pipework so you can heat them both separately, and the other is to run a single zone and simply turn off the radiators where you don't require the heat using smart thermostats. With the later one could still affect the other depending on the diameter of the pipework/insulation.

ispookie666

Simple way to understand - each sensor will act as a zone valve to create a multi zone heating system, with your main thermostat acting as the big boss.  The sensors can be either zone valves or just programmable smart TRV's.  I have an oil boiler and have smart thermostat and 5 eTRV's making it sort of 6 zones, you do need a modulating circulation pump to make this more efficient.  

I don't think having oodles of zones is going to be the most efficient way to run a ASHP.  @Reed_Richards would be able to provide a greater insight.  

greenfalco

QrizB said:

Without more details of the system you've got in mind it's hard to say.

One method is to fit smart valves to every radiator, then control those to achieve the temperature profile you want. That doesn't sound to be quite what you're looking at but it might be.

Astria said:

You have 2 options which I think you have already thought about: one is to create 2 actually different zones with different pipework so you can heat them both separately, and the other is to run a single zone and simply turn off the radiators where you don't require the heat using smart thermostats. With the later one could still affect the other depending on the diameter of the pipework/insulation.

ispookie666 said:

Simple way to understand - each sensor will act as a zone valve to create a multi zone heating system, with your main thermostat acting as the big boss.  The sensors can be either zone valves or just programmable smart TRV's.  I have an oil boiler and have smart thermostat and 5 eTRV's making it sort of 6 zones, you do need a modulating circulation pump to make this more efficient.  

I don't think having oodles of zones is going to be the most efficient way to run a ASHP.  @Reed_Richards would be able to provide a greater insight.  

Thanks for your insights, I hope to find out more as we progress with the build. I think it best to find out how many zones the builder will intends to setup with the ASHP, and go from there...

GF

FreeBear

greenfalco said:  I hope to find out more as we progress with the build. I think it best to find out how many zones the builder will intends to setup with the ASHP, and go from there...

The builder will most likely subcontract the ASHP and heating out to a specialist contractor. You would need to discuss your options with the installer.. Fitting multiple thermostats is going to require a centralised "smart" control (Raspberry Pi perhaps ?) otherwise the thermostats will be competing for control. And unless you are using wireless thermostats, you'll need conduit for the wiring - I'd recommend hard wired thermostats/sensors over wireless. One less point of failure.

I've installed a "smart" home automation system to control the heating. Have a mix of wireless, battery operated, and hard wired sensors scattered around the house. Working out where to run the cables without having to do too much decorating is the next challenge.

Reed_Richards

I have an ASHP running two Zones.  One Zone is bathrooms and it exists so I can heat towel rails when I don't want to heat the rest of the house.  The other zone is the rest of the house.  I have only radiators.

Each zone has a room thermostat, one in the main bathroom and one in the living dining/area.  Other rooms have Thermostatic Radiator Valves (an arrangement which only works if those rooms heat up faster than the rooms with the thermostats).

With UFH and radiators each needs its own zone (at minimum) and your heat pump needs to know that it should reduce the Leaving Water Temperature whenever only the UFH zone is demanding heat.  I'm not sure if that can be done with my model of heat pump but fortunately the situation does not arise.  

matelodave

I have a heatpump which feeds underfloor heating which is divided in eight zones, one for each room. Each room has it's own wireless programmable thermostat which controls the water flow into each of the zones via manifold valves but also turn the heatpump on and off as required.

TBH it's probably overkill and potentially decreases the efficiency of the heatpump as it causes it to short cycle.

My heatpump is 11kw and if just the bathroom or study calls for heat then the heatpump is activated and the flow valves to the particular zone are opened however there's probably insufficient flow to enable the heatpump to run efficiently so it cycles on and off.

There's a bypass valve which maintains flow through the heatpump when the valves close and before they open. The valve actuators are thermally operated and take a minute or so to fully open or fully close. 

It's relatrively easy with an underfloor heating system as all the flow valves are controlled by the manifold controller which receives commands from the room stats but also passes on the command signal to the heatpump.as well as controlling the valves although IMO valves with aux contacts to command the heatpump would probably be more efficient

It's probably more problematic with a hybrid underfloor/radiator system as you'd need a controller that can command the individual rad valves and activate the heatpump as well as the underfloor zone valves.

I'm not 100% convinced that my system is actually the best way to control the system although it seems to work for us. A big problem with underfloor heating is it's very slow response time compare to radiators.

Rads usually run at around 50-60 degrees whereas underfloor is around 35-40. The other problem is that an undefloor system thats buried in concrete will take several hours to warm up and several hours to cool down, just like a storage heater so there's not much point in having responsive thermostats or clever stuff like Hive etc.

Our system takes the best part of 24 hours to get the house back up to temp if we let it get stone cold but as we are home all day then a 2-3 degree set back overnigh suits us

I should think that a hybrid underfloor/rad system needs to be configured as two zones, one running the underfloor with it's own stat and the second with either a single stat for the zone  plus TRVs or wireless TRVs to control the room radiators.

Look at this thread - I bought a Heat Pump - Page 22 — MoneySavingExpert Forum lots of good info on it but I'm not sure that anyone has the ultimate answer because all our requirement differ