Full ASHP / HW / UFH and Zones diagram

[flanagaj]

Does anybody have an example schematic for the above.  In our last house we had a single zone and radiators.  Things have moved on now and I understand that with UFH you have the manifold which allows for n individual circuits, but if I am correct, these are not zones, but simply a way to balance each of the loops.  Much like you would with the valves on a radiator.   So how many zones are people installing.

Again, if anyone has a system design that they can share, that would be great.

Thanks

[JohnMo]

Are mixing the term zones with loops?

 

My house started with 6 zones (7 UFH loops). First two months gas bill was equal to the calculated annual bill. Low energy demand heating systems and zones are a plaque. Avoid, don't even say the name zone.

 

Now run a single zone, no actuators, no valves, no pumps, no mixers, no buffers, no thermostat heat pump does it's own thing, expect a SCoP of mid to high 4s.

 

You really don't need a sketch 

 

Flow side - ASHP to 3 port diverter, one side direct to UFH manifold and other to cylinder coil.

 

Return - UFH manifold to tee, other side of tee to cylinder coil, then to ASHP, via a strainer. Need to add expansion vessel and pressure relief near ASHP and a filling loop.

 

UFH manifold and loop balance - open all flow meters fully. If the odd room is hot trim flow to that loop only, system is balanced.

 

 

[flanagaj]

17 hours ago, JohnMo said:

Are mixing the term zones with loops?

 

My house started with 6 zones (7 UFH loops). First two months gas bill was equal to the calculated annual bill. Low energy demand heating systems and zones are a plaque. Avoid, don't even say the name zone.

 

Now run a single zone, no actuators, no valves, no pumps, no mixers, no buffers, no thermostat heat pump does it's own thing, expect a SCoP of mid to high 4s.

 

You really don't need a sketch 

 

Flow side - ASHP to 3 port diverter, one side direct to UFH manifold and other to cylinder coil.

 

Return - UFH manifold to tee, other side of tee to cylinder coil, then to ASHP, via a strainer. Need to add expansion vessel and pressure relief near ASHP and a filling loop.

 

UFH manifold and loop balance - open all flow meters fully. If the odd room is hot trim flow to that loop only, system is balanced.

 

 

Are you basically saying that you have a single thermostat for the whole house?

[JamesPa]

18 minutes ago, flanagaj said:

Are you basically saying that you have a single thermostat for the whole house

Why bother with a thermostat.  Just use weather compensation.  Seriously!

 

Obviously this is a bit house and person dependent, but for many, pure weather compensation with any 'thermostats'/trvs etc used solely as limiters (ie set a couple of degrees above target) not controllers is the way to go.  It's certainly the most comfortable for my house, way more so than any complex control I have from time to time played with either with my former gas system or my ASHP.  Oh, and it's also very likely to be cheaper doing it this way.

 

The controls industry has taken us for a ride in recent years.  Boilers do weather compensation too, are more efficient if you use it and likely to be more comfortable, yet we instead are encouraged to spend lots of money on overly complex add on controls.  It's time for them to get their comeuppance

Edited July 24 by JamesPa

[JohnMo]

27 minutes ago, flanagaj said:

Are you basically saying that you have a single thermostat for the whole house?

I have zero thermostats. None.

 

Some of my rooms have sensors, but they are just there so I can see what's going on easily, they are not connected to anything for control.

[JohnMo]

26 minutes ago, JamesPa said:

controls industry has taken us for a ride in recent years.

This is true, we are now programmed to think a heating systems must have thermostats and time switches, to work. But if make that step and actually leave the heat source manage this for us, it seems to work and does it pretty well.

 

Our heat pump has zero interactions with the house except the flow and return pipes.

 

It's a bit of a leap if faith mentally at first. Even hot (solar gain) and cold sides of house even themselves out pretty much with no input especially when you have UFH.

[Bramco]

1 hour ago, JohnMo said:

Even hot (solar gain) and cold sides of house even themselves out pretty much with no input especially when you have UFH.

 

So the hot side of the house can't take any heat but the cold side can - so any flow through the hot side comes back still hot whereas the flow through the cool side comes back cooler.

 

Trying to get my head round how this would work for those of us with insulated slabs with UFH that batch charge the slab at night on cheap rate lekky. I guess the same would happen - loops in cooler parts of the slab would suck up more heat than those in warmer parts. 

 

1 hour ago, JohnMo said:

Our heat pump has zero interactions with the house except the flow and return pipes.

 

So the only setting is the setpoint set on the ASHP. What is yours set to against the temperature you are trying to achieve in the house?

[marshian]

2 hours ago, JamesPa said:

Why bother with a thermostat.  Just use weather compensation.  Seriously!

 

Obviously this is a bit house and person dependent, but for many, pure weather compensation with any 'thermostats'/trvs etc used solely as limiters (ie set a couple of degrees above target) not controllers is the way to go.  It's certainly the most comfortable for my house, way more so than any complex control I have from time to time played with either with my former gas system or my ASHP.  Oh, and it's also very likely to be cheaper doing it this way.

 

The controls industry has taken us for a ride in recent years.  Boilers do weather compensation too, are more efficient if you use it and likely to be more comfortable, yet we instead are encouraged to spend lots of money on overly complex add on controls.  It's time for them to get their comeuppance

 

Pretty much what @JamesPa said

 

I'd certainly try WC first with as much of the system in play as possible before adding lots of thermostats and micro zoning

 

I've currently got Wiser "Smart" TRV's on every Rad (13 in total)

 

The only ones that actually have some room influence are on the north facing side of my house with 3 external walls on the rooms and they are used to set back temps during the periods where we aren't using those rooms and overnight for same reason primarily because of the high heat loss.

 

All the others are set to an elevated target temp and act as temp limiters rather than temp controllers (for solar gain on south side or an unexpected and sudden temp change outside)

 

I'm going to try to re-coup some of the cost by selling the smart TRV's and replace them with decorators caps as really they are just expensive battery powered room temp sensors and I have stand alone units already in most rooms

 

[JamesPa]

17 minutes ago, Bramco said:

 

insulated slabs with UFH that batch charge the slab at night on cheap rate lekky. I

If your house has a thermal time constant such that batch charging is practical, then using a room thermostat as a controller isnt going to be much use anyway, because its a 'rear view mirror' - ie it tells the heating what to do when its too late (because of the response time of the house).  That's one of the basic features of weather compensation, it tells the heating what to do before its too late.  

 

The more you think about and actually use weather compensation, the more baffling it becomes that we shunned it for boilers in the UK (unlike some more enlightened countries).

Edited July 24 by JamesPa

[Bramco]

14 minutes ago, JamesPa said:

then using a room thermostat as a controller isnt going to be much use anyway

 

19 minutes ago, marshian said:

All the others are set to an elevated target temp and act as temp limiters

 

The way we use the thermostats is really only for the scheduling and as temp limiters.  The thermostat schedules (3) are set to come on just after the start of the cheap rate and are set in one hour chunks. First hour is at 24C then we drop gradually hour by hour down and the last hours are at 22C.  This ensures that the thermostats don't do their stop start business, so the ASHP is on constantly until the target temperature is reached.  Seems to work for us.

 

If we dropped the thermostats and went over to WC with a setpoint, then we'd have to find some other way of scheduling the night time batch charging of the slab.  So we'll stick with the thermostats.

[marshian]

23 minutes ago, JamesPa said:

The more you think about and actually use weather compensation, the more baffling it becomes that we shunned it for boilers in the UK (unlike some more enlightened countries).

 

reminds me of the Urban Plumbers Skit on Viessmann Boilers and why the company makes life so difficult for installers

 

Skip to 11 mins and enjoy

 

 

 

 

[JamesPa]

1 hour ago, Bramco said:

 

If we dropped the thermostats and went over to WC with a setpoint, then we'd have to find some other way of scheduling the night time batch charging of the slab.  So we'll stick with the thermostats

Fair enough, you aren't really using it as a thermostat though, just a time clock!  Very sensible repurposing of an otherwise redundant piece of kit.

[JohnMo]

2 hours ago, Bramco said:

So the hot side of the house can't take any heat but the cold side can

Pretty much. Floor surface temp is approx 2 degs hotter than room temp, sometimes way less. So solar gain increases room temp. The closer the room and floor temp get the less energy the floor adds to room. Once at same temp floor no longer adds energy to room.  Cooler rooms will continue to take energy from floor.

 

2 hours ago, Bramco said:

batch charge the slab

Different story altogether, you have controls.

 

2 hours ago, Bramco said:

So the only setting is the setpoint set on the ASHP. What is yours set to against the temperature you are trying to achieve in the house

As mentioned there is nothing related to ASHP except flow and return pipes in the house - it doesn't know directly the house temp - but does indirectly via return temp.  Just using a WC curve.  Cooling is basically a single set point but heat pump just modulates or switch the compressor off as needed.

[flanagaj]

So if you don't have an internal thermostat and use weather compensation, how do you control the zone valve to switch the flow off to your UFH and rads?

[marshian]

27 minutes ago, flanagaj said:

So if you don't have an internal thermostat and use weather compensation, how do you control the zone valve to switch the flow off to your UFH and rads?

flipping the question round why would you want to switch the flow off to the UFH and rads if it’s heating season??

 

Well set up weather compensated flow temps should mean that the heat source is only replacing the heat lost not more and not less…..

 

[JohnMo]

1 hour ago, flanagaj said:

how do you control the zone valve to switch the flow off to your UFH and rads

Have no rads and no zone valves. You can run circulation pump (within ASHP) in several modes, continuous, when ASHP compressor runs, and in a mode called sniffer mode (pump runs a couple of minutes every so often or when compressor is on). So circulation is controlled by ASHP. Heating is never off, unless in cooling mode, cooling is never off unless in heating mode.

 

As described in my initial reply, I have a 3 port valve in the system and that's it.