Basic Questions Clarification

[Gaf]

Been reading up on UFH system. Do I have the below right?

 

> Loop: This is a section of the UFH pipe that the water flows through.

> Zone: This is an area of the house 'sectioned' from other areas of the house (e.g. ground floor as zone #1, first floor as zone #2).

> Loops & Zones: More than one loop may be needed to cover the floor area in one zone (e.g. ground floor of 100m2 may need two loops).

> Micro Zone: This is a specific area of the house selected to have a different heating level than another specific area of the house (e.g. bathroom vs sitting room).

> Manifold: The heated water comes to the manifold from the A2W HP. Each loop comes off the manifold and goes into whichever zone of the house it was placed.

> Zoning, Looping, Microzoning: If you have placed separate loops into each individual room in the house (living #1, bathroom #2, dining room #3 etc.) but run all of these microzones at one temperature, then you're still technically running a broader 'zone'.

 

 

[ProDave]

Yes that's about it.

 

Except all the loops from one mainfold will run at the same temperature.  You adjust the heat output to ballance it by adjusting the flow rate to each loop.  Most manifolds have flow meters that allow you to adjust and measure the flow rate to each loop.

 

Whether you have a temperature blending valve on each manifold to set the temperature, or rely on the ASHP doing that is a matter for debate, and whether you have separate zones or run the whole house at the same temperature is another debate.

[Gaf]

2 hours ago, ProDave said:

whether you have separate zones or run the whole house at the same temperature is another debate.

This debate I'd come across alright - seems that most align with running whole house at same temp.

 

 

2 hours ago, ProDave said:

Whether you have a temperature blending valve on each manifold to set the temperature, or rely on the ASHP doing that is a matter for debate,

This debate I hadn't come across. Do most A2W HPs have this as a feature or is it only some models. Ours is going to be Thermia iTec Eco - can't locate a reference to this blending valve with this unit.

[Gaf]

Quick search here seems to suggest blending valve is favoured.

[MrPotts]

You only need a blending valve if you have UFH and radiators unless the radiators are sized for low temperature flow.

Edited January 18 by MrPotts

[Gaf]

1 hour ago, MrPotts said:

You only need a blending valve if you have UFH and radiators unless the radiators are sized for low temperature flow.

Ah. We have no rads…

[JohnMo]

A micro zone is just a zone. With a heat pump zones generally need a buffer, which you really want to avoid. Heat pumps need flow rate to keep them happy and able to modulate. Lots of zones can lead to many being off and say just a bathroom loop on. In this situation without mitigation, the heat pump cannot flow enough water.

 

3 hours ago, Gaf said:

seems that most align with running whole house at same temp

Incorrect, your room temperature comes balancing. Our house is a single zone and we have very different temperatures in bedrooms, on purpose. If anything calls for heat, every loop is on, only going off when everything is satisfied. But we only have two areas of the house able to call for heat. And no actuators on the manifold. We tend to batch charge the floor once per day, as once up to temp the house doesn't vary much over the day.

[torre]

1 hour ago, JohnMo said:

single zone and we have very different temperatures in bedrooms

 

So @JohnMo do you achieve that by just having a slower flow rate to the bedroom loops versus downstairs? I like the simplicity of that but I'm still trying to get used to the idea of not controlling zones independently having had a gas boiler with separate zones for upstairs and downstairs

[JohnMo]

1 minute ago, torre said:

 

So @JohnMo do you achieve that by just having a slower flow rate to the bedroom loops versus downstairs? I like the simplicity of that but I'm still trying to get used to the idea of not controlling zones independently having had a gas boiler with separate zones for upstairs and downstairs

Principal way was to design the loops to match heat loss and target temperature. Balance to get the temperature correct. 

 

But if you are building well insulated do you even need heating in bedrooms? Many on here such as @ProDave live in the Highlands of Scotland and get well below -10, without issue.

 

Plus don't underestimate how long a floor and house retains heat. The thicker the screed the longer the heat is retained.

 

My grand plan was heating all room differently, lots of zones etc.  But the first quarter gas bill killed that - it was over double the expected, mostly due to short cycling, due to small zone being open. I now heat for a few hours and house stays stable the rest of the day. Did try setbacks, but gave up when the timing became 12 hours displaced.

[Gaf]

20 hours ago, JohnMo said:

A micro zone is just a zone. With a heat pump zones generally need a buffer, which you really want to avoid. Heat pumps need flow rate to keep them happy and able to modulate. Lots of zones can lead to many being off and say just a bathroom loop on. In this situation without mitigation, the heat pump cannot flow enough water.

 

Incorrect, your room temperature comes balancing. Our house is a single zone and we have very different temperatures in bedrooms, on purpose. If anything calls for heat, every loop is on, only going off when everything is satisfied. But we only have two areas of the house able to call for heat. And no actuators on the manifold. We tend to batch charge the floor once per day, as once up to temp the house doesn't vary much over the day.

 

With micro zoning, I was trying to differentiate between how it appears 'unzoned' seems to generally refer to having one floor of the house as a single zone, so I was trying to figure out 'unzoned' versus 'zoned' versus 'mircozoned'. For a novice the use of similar terms for different things is tricky.

 

If I'm reading you right, you have one zone but multiple loops? And you've had your loops installed in a manner that there is 'less' / ' more' UFH pipe work (for each loop) in some rooms, and this is how you have managed to balance different room temperatures? So in one room there may be a lot of pipe work, so a lot of heated water gets to this room in the pipes, whereas another room has less pipework, so less heated water gets to this room, all while the same amount of water is flowing?

 

Terminology-wise, what do you mean by a "buffer"? Is that a buffer tank?

 

For us, ours has mostly been installed on ground floor, with thermostats on each room. However, whilst these appear to be unwarranted, my plan was to have all rooms at the same temperature, effectively creating an 'unzoned' ground floor.

 

 

 

 

Edited January 19 by Gaf

[DamonHD]

FWIW I use microzoning to mean control per room or per emitter (eg radiator).

[JohnMo]

12 minutes ago, Gaf said:

zoned

Zoned to me,  just means part of a heating system individually controlled by temperature and or time. So a zone or micro zone is just the same thing.

 

14 minutes ago, Gaf said:

you've had your loops installed in a manner that there is 'less' / ' more' UFH pipe work (for each loop) in some rooms, and this is how you have managed to balance different room temperatures? So in one room there may be a lot of pipe work, so a lot of heat gets to this room, whereas another room has less pipework, so less heat gets to this room, all while the same amount of water is flowing

More or less correct. Water flow rated per loop is based on two thing

 

Loop length, and room temperature. If the room isn't warm enough you increase flow to those affected loops in that room. You do this once when you are balancing the system.

 

At all times I have water being circulated through the whole system (circulation from heat pump is on continuously), there are no actuators on the manifold just manual isolation valves.  A day like we have today is set for an average of 0.5 degs, but with lots of solar gain. So water circulation moves heat about the house, so rooms not currently being heated get the benefits of any heat sucked up from solar heated rooms.

 

21 minutes ago, Gaf said:

installed on ground floor, with thermostats on each room.

So in effect, if you are not careful, all rooms on ground floor have become zones, not one single ground floor zone. If each thermostat is allow to open and close UFH loops and call for heat each is a zone. Having the same temperature in all rooms is not relevant.

 

I will have 6 rooms sensors (not thermostats), but will be using these for monitoring only. Mostly they will have no permission to call for heat. Our hall will in effect be the master thermostat, but kitchen diner can also call for heat, the whole UFH system will get heated water, not just the cool area. So the whole house operates as a single zone.

[Gaf]

4 minutes ago, JohnMo said:

A day like we have today is set for an average of 0.5 degs, but with lots of solar gain. So water circulation moves heat about the house, so rooms not currently being heated get the benefits of any heat sucked up from solar heated rooms.

Ah that's really clever. Had not considered this as a possibility.

 

 

4 minutes ago, JohnMo said:

So in effect, if you are not careful, all rooms on ground floor have become zones, not one single ground floor zone. If each thermostat is allow to open and close UFH loops and call for heat each is a zone. Having the same temperature in all rooms is not relevant.

OK so if we have thermostats that are allowed to open / close loops, and call for heat, we risk a room with say high solar gain heating up to a point the thermostat says "no need for heat in this room anymore" and closes the loop. This could lead to less water flowing, with the heat pump possibly cycling on and off, rather than just running along as it is best.

[JohnMo]

1 minute ago, Gaf said:

thermostat says "no need for heat in this room anymore" and closes the loop. This could lead to less water flowing, with the heat pump possibly cycling on and off, rather than just running along as it is best

I would look at this from a different direction, more worst case. All room are up to temperature, but one room temp drops, so only one loop is calling for heat. No chance of providing heat due to short cycling, would need a bypass and this would just return hot water back to heat pump.

[Gaf]

9 minutes ago, JohnMo said:

I would look at this from a different direction, more worst case. All room are up to temperature, but one room temp drops, so only one loop is calling for heat. No chance of providing heat due to short cycling, would need a bypass and this would just return hot water back to heat pump.

 

Ah. Hmmm. So when the system is being first setup, one way to attempt to mitigate this is getting the balance right when first setting up the system. This probably takes a bit of time tweaking the water flow from the manifold?

 

Sorry, I know I've a tonne of questions.

Edited January 19 by Gaf

[JohnMo]

Wind all thermostats out the way set to say 24. Set system up, you really should set the weather compensation curve now. And balance system.

 

Once all set it should just run on its own.

[Benpointer]

I'm still unconvinced that JohnMo's approach is the best.  

 

I don't want to be trying to set the room temperatures by tweaking the flow rates on individual loops - I just want to set a temperature on a thermostat and be confident that the room/zone will receive heat when the temperature falls >0.5 degrees below the temp set on the stat.

 

Take our south facing ensuite: I want it kept to 23°C.  If I set the flow rate for that room on a cold day cloudy day it will be a higher rate than that required on a sunny day, due to solar gain, and the ensuite will be too hot on those sunny days.

 

Then again when the ensuite has slipped below 23°C, I don't necessarily want the rest of the house including the bedroom next door (target 19°C) to be heated.

 

How much of an issue is a bit of HP cycling from time to time*?  And how does that compare with the annoyance of a heating system that gives you the right temp in each room only some of the time.

 

(*We ran a multi-zone UFH off a Mitsubishi EcoDan for 14 years in our old house with no apparent issues.)

 

 

Edited February 9 by Benpointer

[Iceverge]

5 minutes ago, Benpointer said:

want it kept to 23°C.  If I set the flow rate for that room on a cold day cloudy day it will be a higher rate than that required on a sunny day, due to solar gain, an

 

Isn't the the real beauty of low flow temperature UFH?

 

Say you get your slab to 25⁰, as soon as the room temp hits 25⁰ physics means there's no heat flow any more. 

 

In fact if by some accident the room gets to 30⁰ the 25⁰ UFH should take some heat away. 

 

 

 

 

[Mr Blobby]

On 19/01/2025 at 12:49, JohnMo said:

At all times I have water being circulated through the whole system (circulation from heat pump is on continuously)

 

Do you do this with a pump on the manifold, or with the pump in the heatpump?  

If the latter, then is this a common feature of heatpumps, that the HP pump runs, or can be set to run all the time, even when the thermostat temperature set point is reached?

 

If the thermostat set point is reached and there is no call for heat, then the pump still runs and pumps water round the loops?

 

 

[JohnMo]

35 minutes ago, Benpointer said:

still unconvinced that JohnMo's approach is the best.  

That's fine, what works for you is the way to go. I'm just batch charging again and the house just sits fine for us. 

 

7 minutes ago, Mr Blobby said:

 

Do you do this with a pump on the manifold, or with the pump in the heatpump?  

If the latter, then is this a common feature of heatpumps, that the HP pump runs, or can be set to run all the time, even when the thermostat temperature set point is reached?

 

If the thermostat set point is reached and there is no call for heat, then the pump still runs and pumps water round the loops?

 

 

No pump on manifold. Heat pump circulation pump on 24/7. But batch charging either via heat pump or boiler or both depending on outside temp. All circulation is done by heat pump circulation pump.

 

 

Edited February 9 by JohnMo

[Mr Blobby]

7 minutes ago, JohnMo said:

Heat pump circulation pump on 24/7

 

Is your pump that runs 247 external to the heat pump?  Or inside the HP?

 

I think Panasonic has an internal pump and (I assume from being unable to see anything in the user manual) that this water pump only runs when there is a call for heat.  

Running the pump all the time to distribute heat makes a lot of sense.  Add an additional water pump to do this?

 

 

Edited February 9 by Mr Blobby

[JohnMo]

11 minutes ago, Mr Blobby said:

 

Is your pump that runs 247 external to the heat pump?  Or inside the HP?

 

I think Panasonic has an internal pump and (I assume from being unable to see anything in the user manual) that this water pump only runs when there is a call for heat.  

Running the pump all the time to distribute heat makes a lot of sense.  Add an additional water pump to do this?

 

 

Circulation pump inside heat pump only. To get it to run 24/7 it's on WC. But I can also run two curves, they are changed via a thermostat input. Lower curve heat pump rarely calls for heat, higher curve used for batch charge.

[sharpener]

20 hours ago, Mr Blobby said:

 

Is your pump that runs 247 external to the heat pump?  Or inside the HP?

 

I think Panasonic has an internal pump and (I assume from being unable to see anything in the user manual) that this water pump only runs when there is a call for heat.  

Running the pump all the time to distribute heat makes a lot of sense.  Add an additional water pump to do this?

 

 

 

PMFJI but this depends very much on the manufacturer and settings. E.g. Vaillant Arotherm plus has 3 different Room Temp modes:

1. Inactive. Pure weather comp, flow temp only depends on OAT. Internal pump runs all the time heating is enabled. Useful if controller is in plant room not a habitable room.
2. Active. WC plus load comp, room temp measured at control unit also affects flow temp, will give better control of room temp at the controller(!). Useful for open-plan style houses. Copes with solar gain.
3. Extended. As Active but when room setpoint is reached HP and circulating pump switched off. Saves money but risks other rooms (which can't call for heat) getting too cold.

There is also an auxiliary output which can be used for an external circulating pump in a variety of ways e.g. post-buffer.

[SteamyTea]

UFH pipe spacing is also used to set the amount of power.