Vaillant ashp (my battle with).

[-rick-]

1 minute ago, zoothorn said:

So I'm not clear on whether I could do this, even if I had 30m of specific cable & a day's work drilling through a wall & a ceiling crawling around my attic to re-site this thing to my cold kitchen downstairs.

 

I think @Nickfromwales's suggestion to get a wireless one, that has a reciever that is wired in to your existing may be the easier option. I do think either way though it would be better done by someone else. But I don't know Valliant specifically or whats involved there so will leave this to others.

[zoothorn]

Just now, zoothorn said:

I asked him Rick. It is not easy. It's 6-steps then out again in 4-steps, to put it to ON, on this little thermostat-controller box.

 

If there was a switch on the box, saying Heating ON.. I mean easy, I flick a switch.

I can see the same 6-steps/4-steps & out, to also set the timetr (& also whilst there within the menu, to turn heating to AUTO.. although I can't remembe4 what AUTO even means)..

 

But I thought you didn't want me to set the timer?! Why would you ask me to ask this, to him? (I mean I did, but god only knows why I'm asking it).
 

I'm now getting further confused.

[zoothorn]

@-rick- Here, you say at the end..

 

"Now I have switched to keeping the place at a relatively constant temperature (with a setback) it's much more comfortable and burns less gas than heating from cold every morning".

 

I understand the principle you suggest of 'having the system on' in a continuous way. But here you refer to your continual way "with a setback". The chap told today -& this made my head explode- the following: "You cannot have the heating on, & have a setback setting: the setback setting is for timed blocks".

 

These timed blocks though (I assume the word 'timer' you use ,relates to my current "bad way to do it" setting), is the very setting, you are steering me away from.

 

 

[zoothorn]

Tbh this engineer wasn't the ideal chap. Not too happy being here, short with answers, quite impatient wanting to go asap & coughing continually with a cold.. & I had no choice but cosy up next to him showing me how xyz at the little controller-thermostat box. With a visit to my frail elderly parents soon. Argh!!

 

Why can't anyone who visits like so, just put a fkn face mask on?!! I wasn't too happy as you can appreciate, but I did my best nevertheless.

[-rick-]

11 minutes ago, zoothorn said:

I understand the principle you suggest of 'having the system on' in a continuous way. But here you refer to your continual way "with a setback". The chap told today -& this made my head explode- the following: "You cannot have the heating on, & have a setback setting: the setback setting is for timed blocks".

 

These timed blocks though (I assume the word 'timer' you use ,relates to my current "bad way to do it" setting), is the very setting, you are steering me away from.

 

Ah this is confusing isn't it!

 

Let me try again:

 

The thing we want to avoid is where the heating is full blast for a few hours a day and then entirely off for the rest of the time.

 

We want the system to be on and able to provide heat at any time day or night (if the thermostat says it needs heat).

 

However, it is ok to have the temperature set point vary by time as long as by a small amount. ie it's ok to have the setpoint be 20C in the daytime and 18C at nighttime and use the timer to do this

 

It would not be ok to have 20C in the day and 10C at night as that is too big a difference and it is effectively the same as just turning the system off overnight.

 

Given you have struggled with the system it seems best to keep things as easy as possible. The easiest possible way is to keep the system on 24x7 and use a TRV in your bedroom to lower the temp in your bedroom vs other rooms. Setting up the timer with two different temperatures is the other option but more complicated to do.

 

Edit: You may well need a TRV in the bedroom anyway even if you use the timer for setback because it is better insulated than the rest of the property it is likely to warm up first and end up hotter than the others spaces without a TRV

Edited 9 hours ago by -rick-

[zoothorn]

19 minutes ago, -rick- said:

 

I think @Nickfromwales's suggestion to get a wireless one, that has a reciever that is wired in to your existing may be the easier option. I do think either way though it would be better done by someone else. But I don't know Valliant specifically or whats involved there so will leave this to others.

I can't understand this though Rick. How can a wireless thermostat work: I mean thete's no super-convenient wireless transmitter from the interface box (where the controller-thermostat box's canle originates from).. to transmit to a wireless device.

 

 

 

[-rick-]

Just now, zoothorn said:

I can't understand this though Rick. How can a wireless thermostat work: I mean thete's no super-convenient wireless transmitter from the interface box (where the controller-thermostat box's canle originates from).. to transmit to a wireless device.

 

When you buy it you get two boxes.

 

1. The thermostat that you can put wherever

2. A reciever box that is wired into the heatpump controller.

[zoothorn]

@-rick-

 

I now am confused by setpoint. And setback. As I haven't encountered 'setpoint' terminology, until afaict, today when it's first being used by yourself.

 

I seriously need a break. I am really completely & absolutely baffled with it all now.

 

I'll come back later. Many thanks though, Zoot

[-rick-]

1 minute ago, zoothorn said:

I now am confused by setpoint. And setback. As I haven't encountered 'setpoint' terminology, until afaict, today when it's first being used by yourself.

 

Ah I am sorry.

 

I'm using 'setpoint' to mean the temperature you set the system to deliver.

 

'setback' is used to mean a lower temperature than the one you normally want.

 

So you might set 'setpoint' to 20C for daytime and 'setback' to 18C for nighttime.

 

1 minute ago, zoothorn said:

I'll come back later. Many thanks though, Zoot

 

No problem.

[Big Jimbo]

Poor old Zoot. He has not managed to get himself any further forward. I think he is destined to stay cold and damp forever more.

 

He currently spends £60 per month on his energy bills.

 

Regardless of the well meaning posts on here, we all have to agree that tweeking his system might bring him some small benifits, but ultimately not change a great deal in the way of comfort.

 

The only way that the current situation is going to get better, is by either spending a considerable amount of money on upgrading the house, or considerably more money on energy costs.

 

I don't believe he will want to spend more money on energy costs. he, like me, is obviously a bit of a dinosaur. (I ain't paying £4 for a coffee, when i used to spend 20pence on One 40 odd years ago)

 

I personally don't think that a bit of tweeking of the system, is going to make the Zoot toasty warm. I think that perhaps tweeking the system, and accepting considerably higher bills, is something that the Zoot is either going to have to accept, or remain cold.

[-rick-]

16 minutes ago, Big Jimbo said:

The only way that the current situation is going to get better, is by either spending a considerable amount of money on upgrading the house, or considerably more money on energy costs.

 

That is up to zoot. We have said repeatedly that if he wants to be warmer he will have to spend more, but it is also clear that a lot of what he already spends is wasted.

 

My goal in helping is to get the system to the point where zoot has a choice.

 

How much to spend is variable. Every 1C of internal temperature will cost money. For his current £60 per month if applied wisely his internal temp could be maintained at a level where his breath is not visible. Warm and cosy no, but its still an improvement. Spending more can raise the temperature and once the system is functioning correctly what temperature and how much to spend is completely down to zoot.

[Big Jimbo]

Sorry @-rick- Nobody here can say with any certainty, that the heat that Zoot is currently imputting is wasted. It may simply be that he is not imputting enough ?

 

Zoot is never going to turn on the heating 24 hours a day. He considers that any heating system should be turn on, when you want heat, turn off when you don't.

 

Any heat pump that is run on the basis of, couple of hours in the morning, and a couple of hours in the evening, is simply, not going to work.

 

Unless the mindset is changed, and Zoot himself says it won't. Nothing much is unfortunately going to change.

 

To make any meaningful difference, either more money is going to have to be spent, or nothing much is going to change.

 

As Zoot lives on his own, he may be better to turn the ASHP off completly. Simply turn the immersion on if he wants to have a bath, and concentrate of keeping himself warm, as he does now, with a sleeping bag over his lower half, and a scarf and hat. He might actually save some of his £70 per month.

 

If all the well meaning people on here, actually persuade Zoot, to turn his ASHP on 24 hours a day, we might end up causing the poor fella to be in a very difficult position when the Electric bill lands on his mat.

 

I have stated before that i expect that to be able to put enough energy into a leaky old stone cottage, that is prob about 1200 square foot, would be in the region of £250 per month, over the year.

 

The guy believes that it is not possible to heat his cottage, and for £70 per month he is prob right.

 

£200 spent on a ski suit might be a better bet.

[SimonD]

This thread is very long so I don't know whether it's happened already, but would @zoothorn consider sharing the survey document showing the house heat loss, the model of his new heat pump and perhaps even the radiators sizes and types he's got installed? That way we could perhaps formulate an answer based on the facts of the situation and know how leaky the house is?. Or maybe an EPC certificate, that way it's possible to do a performance estimate on flow temps. 

[-rick-]

28 minutes ago, Big Jimbo said:

Sorry @-rick- Nobody here can say with any certainty, that the heat that Zoot is currently imputting is wasted. It may simply be that he is not imputting enough ?

 

£60 worth of heat should be enough to keep the inside warmer than the outside if applied correctly. That there are times when this is not the case strongly suggests the current energy use is not being used optimally.

 

28 minutes ago, Big Jimbo said:

Zoot is never going to turn on the heating 24 hours a day. He considers that any heating system should be turn on, when you want heat, turn off when you don't.

 

We have asked him to try and his recent posts suggests he is considering it. The proof is in the pudding. If he tries it and it works then he can decide what to do with that knowledge. If he doesn't try he never knows.

 

28 minutes ago, Big Jimbo said:

Any heat pump that is run on the basis of, couple of hours in the morning, and a couple of hours in the evening, is simply, not going to work.

In this house I agree. Well insulated houses it could work, just wouldnt be very efficient.

 

28 minutes ago, Big Jimbo said:

Unless the mindset is changed, and Zoot himself says it won't. Nothing much is unfortunately going to change.

 

I think recent posts suggests Zoot is willing to try and see what happens so long as his bedroom can be kept reasonable for him to sleep in.

 

28 minutes ago, Big Jimbo said:

As Zoot lives on his own, he may be better to turn the ASHP off completly. Simply turn the immersion on if he wants to have a bath, and concentrate of keeping himself warm, as he does now, with a sleeping bag over his lower half, and a scarf and hat. He might actually save some of his £70 per month.

 

Using the heatpump to just heat the water and turning off the rads, may indeed work out better if the budget is strictly set, using the immersion seems like an unnecessary waste given he has a heatpump can do the same job at 2.5x the efficiency (depending on the length of pipes see JohnMo's example).

 

28 minutes ago, Big Jimbo said:

If all the well meaning people on here, actually persuade Zoot, to turn his ASHP on 24 hours a day, we might end up causing the poor fella to be in a very difficult position when the Electric bill lands on his mat.

 

If he decides to go ahead part of my suggestion is to monitor the meter closely (stated much earlier and would do again if we get to that point). It is certainly the case that running the experiment for a couple of weeks will add cost, but I suspect averaged over the year it won't make much difference for the experiment. Long term is different, after the experiement Zoot will have information needed to make decisions.

 

28 minutes ago, Big Jimbo said:

I have stated before that i expect that to be able to put enough energy into a leaky old stone cottage, that is prob about 1200 square foot, would be in the region of £250 per month, over the year.

 

What is enough? It depends what temperature you want the inside. Every 1C costs a lot, lowering the thermostat gives zoot flexibility. I think it's realistic for not much more money to get zoot to the point where he still needs a blanket in his sitting room but while sitting there with his blanket he feels comfortable rather than still cold. I suspect £250 per month over the year gets the place to approximately cozy.

 

I've said before my mums place costs about £2000 a year to heat. Thats with uninsulated solid brick walls (some only single skin). That's £160 per month averaged. Zoots walls being super thick likely have a higher U value than my mums.

[Gone West]

4 hours ago, zoothorn said:

therefore all rooms more or less, with rads on dipping in-out to 18*C, for 8 hours, when I'm not using any.. is to me fundamentally absurdly wasteful

It's a shame Zoot that you aren't able to understand that your way of wanting to heat your type of house is 'fundamentally absurdly wasteful'. By letting the rooms cool down over night you would then be using more energy to heat them up again the next day, rather than leaving them heated all the time. If you want to heat a house that way you should move to a more modern house. As I have said before my house is a very similar type of construction to yours and is in a very damp part of the country, it is heated 24/7 and kept at 23C. It's not cheap but a 30kW oil fired Aga does the job.

[-rick-]

1 hour ago, -rick- said:

What is enough? It depends what temperature you want the inside. Every 1C costs a lot, lowering the thermostat gives zoot flexibility

 

I've been thinking about this and wanted to put some numbers on it.

 

Taking a hypothetical two storey 120m2 building with 2ft stone walls.

 

6x10x5 footprint. Assume worst case U-value of walls (from scottish gvt doc) of 2. Relatively poor double glazed windows, also 2 (makes calc easy).

 

Wall area 10x5x2 + 6x5x2 = 100 + 60 = 160 m2 of wall

 

Heatloss through wall per C of difference between inside and outside = 160 * 2 = 320W

 

Heat input requried (Watts)

 

	Average Outside Temp
Inside temp	0	3	6	9	12
15	4800	3840	2880	1920	960
16	5120	4160	3200	2240	1280
17	5440	4480	3520	2560	1600
18	5760	4800	3840	2880	1920
19	6080	5120	4160	3200	2240
20	6400	5440	4480	3520	2560
Approximate cost for 1 month/30days at 25p/kwh
	Average Outside Temp
Inside temp	0	3	6	9	12
15	288	230.4	172.8	115.2	57.6
16	307.2	249.6	192	134.4	76.8
17	326.4	268.8	211.2	153.6	96
18	345.6	288	230.4	172.8	115.2
19	364.8	307.2	249.6	192	134.4
20	384	326.4	268.8	211.2	153.6

 

So if we assume that for the year the outside temp averages 0 for one month, 3 for 1 month, 6 for two months and 12 for two months. (6 month heating season) and a SCOP of 3.

 

Annual spend on energy would be (ignoring DHW):

 

Inside temp
15	979.2
16	1094.4
17	1209.6
18	1324.8
19	1440
20	1555.2

 

Obviously a lot of assumptions here (ignoring losses through roof and drafts, ignoring modern extension, taking likely worst case U value for walls and COP). As a sanity check Nick said his similar property cost him £450 for a month to maintain at 19.5C. I'm assuming that's not averaged over the year but what it costs mid winter in which case it's not far off these approximations.

 

The difference by degree C is lower than I was expecting but I think these are still useful numbers and I think shows zoot could likely maintain an internal temp of about 16 without spending significantly more. If with our help he can get to a COP of 4.5 on his heatpump then he could do better. If there are significant drafts then all bets are off, but drafts can be fixed.

[zoothorn]

@-rick-

 

Ok I'm tentatively back to try understanding xyz. The setpoint.. good ok so that's obviously simple/ understood.

 

Right just a couple of things. Firstly my £72 (not £60! The cheek! You see y'all are already breaking my balls!) is not just HP expenditure is it. I mean..

 

1) I'm one person, always here/ happy loner tbh

2) I never use hot tap, shave/ face am/ dishes, nowt.
3) I don't have live TV & only watch 2x dvd's a week.

4) I only ever use 1 cooker ring. Never once turned the others on in 10yrs. And I try keep it on for 15 mins.

5) 1x a month I use 190*C oven, 35 mins max.

6) I'm so used to my sofa mini leccy blanket, I often listen to records (small leccy useage hobby) + a hottie on my back, seeing my breath: get used to it.

7) No dishwasher.

8 ) Don't have a WM dryer/ put clothes outside to dry.

9) All lights off in rooms I'm not in.

 

I do use baths, cos it's so cold in bathroom in winter, if I use the shower, my plums ascend (imagine a cold, plucked Turkey called Zoot). I have to take baths in winter, but not every day mind.

 

That is my 1st point.

 

Zoot

 

 

Edited 3 hours ago by zoothorn

[sharpener]

On 22/02/2026 at 14:09, Nickfromwales said:

The extra room stat would take command of the times and temp, and would avoid you needing to learn how to make these changes on the fixed controller that came with the ASHP.

 

Unfortunately @zoothorn has a Vaillant HP so it is not so simple. But it can be done.

 

For most practical purposes the installation has to have at least one VR720 Sensocomfort controller. These come wired or wireless. The outside air temp sensor has to be the same type, so if you are swapping the one you have to swap the other as well. The wireless OAT sensors are not as reliable.

 

IIRC you can add extra wireless thermostats, which are cheaper, but only if the Sensocomfort is already wireless. You would still need to change that so it wouldn't help.

 

So a toss-up, as swapping all the hardware probably not much different from paying someone to move the wired controller. There is no practical limit on distance as the ebus only requires plain twinflex.

 

You can make a Vaillant system work with an ordinary central heating timer wired directly to the outdoor unit, but as you still need a Sensocomfort to set up most of the zone parameters, I wouldn't recommend going down this route.

 

On the whole I would suggest enabling the HP 24/7, with bedroom rads switched off at night with their lockshield valves or smart TRVs and the rest of the house on a chunky 5 deg setback.

[Big Jimbo]

Zoot the Hoot. i love ya fella. Except for the setback bit (I think you are talking Balls, about now understanding that ).

Every other thing you wrote......I could have guessed. Fair play, you are you're own man, and you play it you're way.

Hats off to you my friend.

Personally, due to being a lifelong smoker, i suffer a bit with cold feet. A hottie on those tootsies, and i'm happy as a pig in poo.

 

Long live Zoot the Hoot. (ain't nobody gonna tell him how to play the game)

 

My sincere best wishes to you pal. If i didn't have a long standing wife, i could see myself being very similar. The only difference is i would have Six rescue dogs, and perhaps the treat,  of a lady of the night when funds allowed. (Just as a workout for the old ticker)

[ProDave]

So Zoot is having trouble understanding anything that is written on this forum.  And todays installer has proved completely useless at adjusting anything or explaining how to adjust things.  He just wanted to show face to check nothing was actually broken and make a smart exit.

 

I honestly think the only way Zoot will get any improvement is if he were to pay for the services of someone who actually knows and understands this stuff to visit him and adjust what is necessary and show him what he has done and why.  That will cost him some money and you NEED to make sure it is someone recommended and truly knowledgable and competent.  (for instance I would recommend @Nickfromwales )

[-rick-]

18 minutes ago, zoothorn said:

Right just a couple of things. Firstly my £72 (not £60! The cheek! You see y'all are already breaking my balls!) is not just HP expenditure is it. I mean..

 

Can't remember where the £60 comes from but I know I assumed £60 was pure heatpump cost, with the other £12 being other costs + standing charge, a guestimate of course. (likely a little off as my Octopus standing charge is about £12)

 

[zoothorn]

@Big Jimbo I'm really not trying to be deliberately obdurate. I am genuinely trying to understand. It's just it doesn't follow logic, to me. I have to shift this mindset, or plough on trying.

 

I got confused with the setback & setpoint.
 

My second point I wanted to make, is to reiterate, that the chap today said the following..

 

"You can't have a setback setting, with the heating set to ON.. you can only dial in a setback, with a timed situation setting".

 

IE what I had before, with my 2 blocks of timed AM & PM heating goes only periods.. had a setback of 12*C.

 

So I am resolutely STUCK for understanding here, because the consensus is persuading me to dial in a Setback AND ALSO have he heating set to permanently ON.

 

I can only cope, with addresssing my first point (my very meager useage as to why my £72 might make more sense than it did)... & my second point, this Setback conundrum which my head cannot cope with right now. Total & sheer confusion with this, after today's engineer visit,

 

Thanks Zoot
 

 

 

 

Edited 3 hours ago by zoothorn

[-rick-]

10 minutes ago, zoothorn said:

My second point I wanted to make, is to reiterate, that the chap today said the following..

 

"You can't have a setback setting, with the heating set to ON.. you can only dial in a setback, with a timed situation setting".

 

So I am resolutely STUCK for understanding here, because the consensus is persuading me to dial in a Setback. 

 

Let me have a run at this. If this doesn't click try to expand on what aspect isn't clicking.

 

Your system has three different ways of running.

 

• Heating always available (ON if the room temp is below the setpoint temperature) - we are refering to this as 'ON'
• Heating is not available, 'OFF'
• Auto/Timer

In Timer mode, the system is always in the ON state BUT the setpoint temperature changes according to the timer. You can make this really complex if you want. You could say at 9am you want it to be 25C, 12pm 20C, 8pm 25C, 12am 10C, etc

 

Most people use the timer to set a daytime/'at home' temperature 'setpoint' and a nighttime/'not at home' temperature 'setback', but you don't have to do that.

 

Right now your system is likely set up to have one temperature during the 2 hours each morning and evening and a 'setback' temperature that is much lower the rest of the time. So it's never really off, just that the temperature outside those 2 hour periods is set low enough that the system never turns on. The minimum temperature setting is usually 'Frost Protection' which means the only time it comes on is if it gets so cold the heatpump might freeze which would damage it.

Edited 3 hours ago by -rick-

[zoothorn]

@-rick-

 

Ok let me just try to understand this. I need to boil it right down, to incrimental steps now. I'm almost completely deluged. It's been getting muddier, not clearer, today for me.

 

Why is there an Auto/ Timer setting at all then, if y'all are telling me that this way (which I have this new HP set like) is completely wrong for a HP to run like this/ do it completely differently y'all say etc.

 

I mean, if this Auto/ Timer setting, is one out of three options, as to how you can basically set it........ then there must be some logic, to set it, using the Auto/ Timer way.

 

Who would set it like so?? There must be, & I'd surmise, therefore 1/3rd of those who have these HP's, who have it set to Auto/ Timer.
 

And so why, shouldn't that include me-?

 

Thanks, Zoot

 

[sharpener]

7 hours ago, zoothorn said:

@-rick-

 

I've had engineer visit (couldn't find any fault- but putting that no HW anomally aside)..

 

I put your post to him, he read your actual post. And answered the questions, & I scribbled down best I could.

 

Ok first thing I noticed him say, was if I put the heating to ON (IE permanently) I -cannot- also then dial in a 'setback' temp. This 'seback' he said was only in conjunction with the heating set to blocks of time.

 

So immediately a spanner in the works. And I don't know where I'm at now on this. The setback was a fundamental thing I need, in order for the heating once it's got up to temp, to not dip below. So further confusion for me.

 

 

The three fundamental modes on a Vaillant are

 

• OFF
• Time Control (with programmable Schedule)
• Manual (always ON)

 

If you are to have Setback i.e. a different temp at certain times you have to programme the times, which is why Setback is only meaningful if you are in Time Control mode. This mode allows you to program different temps with a time resolution of 10 mins.

 

7 hours ago, zoothorn said:

It is not easy. It's 6-steps then out again in 4-steps, to put it to ON, on this little thermostat-controller box.

 

If there was a switch on the box, saying Heating ON.. I mean easy, I flick a switch.

 

 

You can wire a simple switch across two terminals in the outdoor unit. Or a "normal" central heating controller. This might suit you. As noted above the interface with the phone app is better.

 

The "engineer" does not seem to know much about these systems. In particular the statement that the controller has/needs a 240V supply is not correct. It is supplied at low voltage by the two-wire ebus connection, this does not have to be taken from anywhere in particular so you can connect the controller to the VWZ AI Appliance Interface (white controller), the outdoor unit, or anywhere along the cable connecting the two.

It is the internet interface box that needs a 240V supply.

 

 

7 hours ago, zoothorn said:

The next thing. I asked if 1 radiator can have a TRV on, to stop this overnight rads situation in my bedroom, which afaict, is forced on me if I choose heating ON setting (which now seems less conjusive to me, than before). He said yes.

 

I asked him if I can turn 1 radiator off fully/ always (my workshop, which seems hugely wasteful being the warmest room, but that I spend the least time in). Yes.
 

Trouble also is, to set my heating to ON, is very complicated: I can't just press 2 buttons to set it to ON. No. I have to go into menu & do 6 steps, then back/ back/ etc & out again. Ridiculous. I can't possibly be expected to do this, remember this, each time. Urgh.

 

 

 

So I think I'm just as confused as I was before he visited!

 

Thanks Zoot