Vaillant ashp (my battle with).

[marshian]

14 minutes ago, zoothorn said:

Hi marshian,

 

ok good so I get the general gist of this, but cannot glean an answer from your reply as to 'what is a medium setting I need to put (this flow temp to) with efficiency in mind'.

 

Forgive me but I can't use your 70% figure to do anything wth, other than see it's a high percentage number; more than that, it remains completely arbitrary.

 

Are you meant to 1) assume the installer sets this flow temp to a default factory setting, or set it yourself day 1, or I don't know, do calculations of some kind, to know what to set it to-?

Thanks, Zoot

 

 

What Flow temp you need is simple - the lowest flow temp required to heat the house with the rads you have 

 

My house with a gas boiler is between 25 and 35 depending on outside temp............ But I did fit big rads so that I could do low flow temps

[marshian]

15 minutes ago, -rick- said:

But equally, your heatpump will produce more heat output per unit of energy input the lower the temperature. So if your set the output temp to 55C it might take 1kw input to produce 2.5kw output. But if you set the output temp to 35C it might take 0.5kw to produce 2.5kw output. So double the amount of heat for the same money.

 

No point saving money with a lower flow temp if the house remains freezing 😉 

 

15 minutes ago, -rick- said:

Zoot said his current flow temp is set at 46C. That sounds fine for now to me. I would leave that as is.

 

We don't want @zoothorn cooking though do we 😉 

 

15 minutes ago, -rick- said:

The aim is to set it as low as possible while still outputting enough heat to be warm. Right now there are other issues stopping zoot from warming up.

 

I'd start in the middle (35 Deg) and see where the house settles - increase or decrease accordingly

[-rick-]

Just now, marshian said:

I'd start in the middle (35 Deg) and see where the house settles - increase or decrease accordingly

 

I'd very strongly advise not touching it at all right now. Zoot has mentioned that this new system is the first time he has felt as if the system is working and outputting some warmth. Once the other issues we've talked about have been solved and the building is warm then we can talk about lowering this. But I think it's a really bad idea to lower it now before we have got the building warm.

 

Zoot, in my view, you could increase the hot water temp to 55 rather than 46 if you want but don't touch the flow temp for the rads. Focus on figuring out how to adjust the timer and locating the thermostat in the right location.

[zoothorn]

1 minute ago, -rick- said:

 

Why not in the sitting room?

 

What about at the bottom of the stairs?

 

 

You can set up whatever periods you like in the timer. Lower temp at night higher temp during the day is about the simpliest way to do it.

 

 

As we have said repeatedly, setting it that low overnight means your system will be overwhelmed by the cold. To maintain a comfortable temperature during the day you will need to maintain a higher temp at night.

 

Having the temperature set a bit lower overnight is fine, but more than a few degrees will cause the heatpump too much work and the house will become too cold to heat.

 

I know this sounds wrong to you and you don't like the idea, but all we are asking is you give it a go. We can work with you to find a solution for your bedroom so you can sleep comfortably, but the rest of the house should be kept relatively stable temperature (+/- 2-3 degrees).

Hi Rick,

 

bottom of the stairs, actually IS in my sittingroom! Haha, so seriously there's not any good place for it anywhere in this cottage, was my point tbh.
 

It's case of the least-worst option. Which is likely not much different to where it is tbh: this room is never warm, it's slightly warmer than the others only. That's still damn cold, due to the construction.

 

Because the cottage has these construction caveats (the plasterboard redo upstairs job just to aid one small bit of it... is a massive undertaking for me, hugely inny-outy complex, 4 windows to go around, with 4 box-affair fake wall areas to recreate. Plus I renovated both rooms in last 6 years, up to how they look now/ finished/ so a galling prospect)... even if I upped the heating, when it gets up to speed & trips off, it would then go cold again far quicker than any insulated house. Meaning it would have to be going on-off-on far more often. Meaning my heating bill won't just be bigger, it'll be hugely bigger. That's using plain logic. 
 

This is where to me, addressing the main sittingroom floor, could only really be considered IME. I asked the latest installer (the Vaillant trained-up competent one, with his £70k electric van outside) if I did redo floor in here, could I disconnect the two big double rads, & connect the HP up to a UFH circuit here? IE a UFH 'ring' sizewise  directly similar to these two bigass double rads. Yes he said. Furthermore he said it was a decent idea, & connection to the cylinder easy, due to it being directly above/ pipe just comes straight down 2m, albeit 2x bit larger diameter copper pipes.

 

I could only really consider the logistics of this renovation job, not removing all the plasterboard in 2 bedrooms above. I could try the small holes > input foam, in the perimeter. But the floor between the rooms hasn't thickness for even 1" of insulation to be introduced. 

Anyway, still trying to plan how I can use the HP/ setting etc. The fact that you seem t9 concur that an overnight setting CAN be dialed in, separate from the Auto/ Timer setting (which I now believe to be the one suggested), means I can do that then. Even if not optimal for your suggested way, I can at least have it set lower. No choice- I have to have it set like so. Besides, it does clearly imply by design, that a lower setting overnight is perhaps even 'standard fayre' (or what's the moon symbol even for?).

 

Thanks, Zoot

 

 

 

 

 

 

 

 

[zoothorn]

31 minutes ago, marshian said:

 

What Flow temp you need is simple - the lowest flow temp required to heat the house with the rads you have 

 

My house with a gas boiler is between 25 and 35 depending on outside temp............ But I did fit big rads so that I could do low flow temps

Understand the logic in this reply. But even so, that doesn't answer my question of basically "what do I set mine to?". (Unless you are suggesting "set it to 30*C Flow temp, that is a general medium number, for UK households").
 

I don't understand whether I have optimal rads for here, sub-optimal rads for here, I don't know if you're privvy to a plethora of U value calculations to know abc, xyz. Furthermore you have a gas CH system. A HP system is by nature a different way of doing things: generally speaking bigger rads that output lower than gas CH systems. This therefore is perhaps going to mean a fundamentally different Flow temp.. I mean isn't it?

Thanks, Zoot

Edited 4 hours ago by zoothorn

[marshian]

1 hour ago, zoothorn said:

Understand the logic in this reply. But even so, that doesn't answer my question of basically "what do I set mine to?". (Unless you are suggesting "set it to 30*C Flow temp, that is a general medium number, for UK households").

 

I'm just saying start low (ish) and work your way up if the house remains cold - I have this irrational fear that you will start high, pronounce the house too hot, can't sleep and turn it off again

 

People tolerances are different - I'm "hot" above 19 - Mrs Alien - different kettle of fish less than 21 is freezing!!!!

 

1 hour ago, zoothorn said:

I don't understand whether I have optimal rads for here, sub-optimal rads for here, I don't know if you're privvy to a plethora of U value calculations to know abc, xyz. 

 

Well we can start there - what size and type are the rads and what sizes are the rooms - we have enough knowledge on here to start piecing it all together and come up with a reasonable punt 

 

1 hour ago, zoothorn said:

Furthermore you have a gas CH system. A HP system is by nature a different way of doing things: generally speaking bigger rads that output lower than gas CH systems. This therefore is perhaps going to mean a fundamentally different Flow temp.. I mean isn't it?

 

I have a gas boiler and I'm running it like an ASHP - CH 24/7 low flow temps (between 25 and 35 Deg C based on weather comp) - when doing HW it raises the flow temp to heat the tank.

 

I could replace it with a 5kW HP tomorrow and know it would work perfectly - this was the point of my rad upgrades and insulation improvements - get HP ready without leaping into it and then finding all my calcs were wrong and I've got a problem.