Where to put plumby bits?

[Nickfromwales]

2 minutes ago, G and J said:

The all in one thingy is the next step beyond preplumbed, if I’ve understood correctly.  It’s this kind of thing:

https://bpcventilation.com/products/aquarea-all-in-one-water-to-air-heat-pump?variant=53736366866758

 

If I don’t go for the all in one type unit then there’s a choice re pre plumbed vs naked.   I would naturally err towards naked but some of the pre plumbed ones do look ridiculously neat!  My assumption would be I’d save money and a bit more choice on placement with naked, and our utility room is not going to be terribly spacious.

That’s a split unit, with gas lines between the internal and external units. Needs an F-gas installer.
 

Not a horrible option but looks to then become an expensive install! Prob just doubled your installed cost there vs buying boxes and connecting via a local ‘but competent’ plumber.
 

Can’t see much info about DHW (recovery times etc) other than it’s a 200L tank, but I’m not trying too hard today lol. 

 

I’d also want to know how noisy the outdoor unit gets when doing DHW.
 

The monoblock Aquerea I’ve just fired up is crazy quiet when going full chat to heat 400L of DHW from standstill for the 1st time.

 

“Panasonic All in One air to water heat pumps should be installed by a qualified installer and preferably an approved Panasonic heat pumps engineer

To purchase this heat pump, we will require the installers details and currant F-Gas number before it is dispatched”  

[JohnMo]

19 minutes ago, G and J said:

utility room is not going to be terribly spacious.

So why the bulk of the all in one then? It basically moves most the stuff of a monobloc inside? Big box small cylinder and from the looks a £1k plus cost premium. Easy plumbing for a premium price.

 

19 minutes ago, G and J said:

pre plumbed ones do look ridiculously neat!

Until you realise most the time in points are exactly where you want them, they have zone valves not needed, basically plumped for S plan or similar, which you don't want.

 

My 210L came with 3 port diverter, expansion vessel, combi valve, and elbows, for under £1k, pre plumbed was nearer £2k, piping in wrong place for easy tie-ins, loads of stuff not needed.

 

[G and J]

1 minute ago, Nickfromwales said:

That’s a split unit, with gas lines between the internal and external units. Needs an F-gas installer.
 

Not a horrible option but looks to then become an expensive install! Prob just doubled your installed cost there vs buying boxes and connecting via a local ‘but competent’ plumber.
 

Can’t see much info about DHW (recovery times etc) other than it’s a 200L tank, but I’m not trying too hard today lol. 

 

I’d also want to know how noisy the outdoor unit gets when doing DHW.
 

The monoblock Aquerea I’ve just fired up is crazy quiet when going full chat to heat 400L of DHW from standstill for the 1st time.

 

 

“Panasonic All in One air to water heat pumps should be installed by a qualified installer and preferably an approved Panasonic heat pumps engineer

To purchase this heat pump, we will require the installers details and currant F-Gas number before it is dispatched”  

OK, I admit it, I grabbed the first link I could find - sorry.  
 

The units I’ve been looking at use a monoblock ASHP and the indoor unit is like a cylinder and lots else wrapped up in a steel box to make it look like a freezer.  I think you connect the ASHP flow and return to the unit, thence the flow and return to the UFH manifolds, the cold water feed and the DHW output and thats it.  Super quick instal giving a really neat unit.   I’ll try find a link to the right one…

 

 

[JohnMo]

8 minutes ago, Nickfromwales said:

All in One

Forgot to mention - one thing goes wrong generally the whole thing is toast.  Monobloc and 3rd party cylinder every day.

[G and J]

1 minute ago, JohnMo said:

Forgot to mention - one thing goes wrong generally the whole thing is toast.  Monobloc and 3rd party cylinder every day.

That had occurred, but I’ve history of excessive Ludditery, so I thought it best to seek the opinions of other's.

 

Here's one of the units ….

https://www.viessmann.co.uk/en/products/heat-pump/vitocal-151a.html

[Nickfromwales]

5 minutes ago, G and J said:

OK, I admit it, I grabbed the first link I could find - sorry.  
 

The units I’ve been looking at use a monoblock ASHP and the indoor unit is like a cylinder and lots else wrapped up in a steel box to make it look like a freezer.  I think you connect the ASHP flow and return to the unit, thence the flow and return to the UFH manifolds, the cold water feed and the DHW output and thats it.  Super quick instal giving a really neat unit.   I’ll try find a link to the right one…

 

 

The fully compact / modular boxes are all “gas” powered I suspect, that’s how they can make it physically smaller. The conversion happens once not twice then as energy is released direct to the heat exchanger in the cylinder vs 2x conversions gas > wet then wet > wet. 

[G and J]

My base assumption would be to assemble myself from parts, but I can’t trust my instincts as it never occurs to me that sometimes factory built has advantages.  
 

Re the underground pipe surfacing just inside the house, I got that idea from a post on here, but I wanted the joint accessible.  On the bright side, each idea identified as stoopid gets me closer to a sensible design - so I should (and do) welcome my embarrassment.  🙂 

[Nickfromwales]

2 minutes ago, G and J said:

That had occurred, but I’ve history of excessive Ludditery, so I thought it best to seek the opinions of other's.

 

Here's one of the units ….

https://www.viessmann.co.uk/en/products/heat-pump/vitocal-151a.html

Another “high temp” split methinks. 70°C is beyond most monoblocks. 

[G and J]

Plan D1 with naked UVC it is then.  
 

Thank you for helping me cap off daft options guys.

[G and J]

So I chose me ASHP, which will have a water pump built in.  
 

On the specs of that will be a limit to pipe resistance. So I add up my pipe resistances and compare, maybe using oversize underground pipes to help, and I either smile broadly or I plan in a return pump under my stairs to work in tandem with the ASHP water pump.  
 

Still looking at a single zone doing everything, just two 2 port valves, using weather compensation, a 250l UVC heated to maybe 50C.   Oh and we want a switch that says heating - off - cooling.  That’s the truly inspired bit.
 

Am I getting warmer?

Edited April 21 by G and J

[G and J]

Oh, and I’ll buy some extra soft HB pencils so my knees don’t hurt too much….

[Iceverge]

I'm not a fan of putting an ASHP so far away from the house. It's UFH for your garden even with the insulated pipes. 

 

Can you not put it closer to the house. They really are not that noisy. 

 

 

If you can get a 300l cylinder in place I would do that. They're only fractionally dearer than a 250l and offer about the best bang for your buck. Remember the larger the DHW cylinder the cooler you can run it, less electricity, less noise from the ASHP. 

 

 

 

 

[G and J]

2 hours ago, Iceverge said:

I'm not a fan of putting an ASHP so far away from the house. It's UFH for your garden even with the insulated pipes. 

 

Can you not put it closer to the house. They really are not that noisy. 

We've been round this one soooooo many times.  
 

It can’t go either side, too close to the boundaries.  
 

It could go right by the front door - lovely.

 

Or it could go near the road and impede a parking space.  

 

Or it could go on the patio by the patio doors.  Not ideal either. 
 

In reality the sensible choice was to give up on an ASHP and fit a gas boiler, but, as a matter of principle, we wanted no gas.  So instead we are shelling out on an expensive pipe, and accepting slightly higher running costs.  We think it is still ecologically better than a gas boiler.

 

2 hours ago, Iceverge said:

If you can get a 300l cylinder in place I would do that. They're only fractionally dearer than a 250l and offer about the best bang for your buck. Remember the larger the DHW cylinder the cooler you can run it, less electricity, less noise from the ASHP. 

And if I can get a 300l one in the utility room without making the cupboards deeper I will.  Ta for the link - haven’t buttoned down the cylinder yet.

[Nick Laslett]

36 minutes ago, G and J said:

 

In reality the sensible choice was to give up on an ASHP and fit a gas boiler, but, as a matter of principle, we wanted no gas.  So instead we are shelling out on an expensive pipe, and accepting slightly higher running costs.  We think it is still ecologically better than a gas boiler.

 

@G and J, if you are already on mains gas? Then there is no shame in fitting a gas boiler. Gas is the cleanest of the fossil fuels. Most of our electricity comes from gas. So even if you have an ASHP, you are using gas most of the time. Burning gas locally is more efficient than burning gas at the power station. 

 

 

By building a well insulated, airtight house you are already making a long term commitment to the environment. Your personal carbon footprint from using a tiny amount of gas for your domestic hot water and heating, in comparison is insignificant. 
 

This calculator is a useful tool for modelling these choices. 
 

https://students.open.ac.uk/candc/carbon_calculator/

 

If your situation allowed for you to easily fit an ASHP, then it would be different. But there are millions of dwelling in the UK, where fitting an ASHP will be a real challenge. 
 

Just my thoughts on this topic specific to your situation, I don’t want to upset anybody. There are far worse things than a brand new high efficiency weather compensation driven gas boiler for the environment. 

Edited April 21 by Nick Laslett

[JohnMo]

1 hour ago, Nick Laslett said:

no shame in fitting a gas boiler

I found with boiler it's super efficient at heating via UFH. I run at a fixed temperature, chosen so the boiler runs without stopping when ever it's on (when it's been below 5 degs for more than 6 hrs - hybrid install). And running against a heat pump cylinder generally runs about 4 degs hotter than the cylinder ends up. So about 56 degs max temperature.

[G and J]

Oh we did have mains gas.  Paid £1.7k to have it removed.  
 

Going electric only feels right, for the warm fuzzy doing the right thing internal feeling kinda reason.   Just need to work the choices that follow that.  
 

I’ve read a good few instances of moderately extended pipe work for ASHPs appearing to work ok, so we’ve gone for it.
 

Just need to find the right ASHP and cylinder now.

 

 

[JohnMo]

3 minutes ago, G and J said:

right ASHP and cylinder now

Buying at full price, I would go Panasonic monobloc and just go to City Plumbing or Cylinder2Go (you get a discount )for the cylinder. Then you just need an UFH manifold.

 

Next job - do your pressure drop calculation assume a 100m long UFH loop and then use your pipe length to sort out primary feed pipe sizes. You want to be getting around 1.4m³/h flow rate (assuming 6kW), to keep UFH and cylinder happy.

[G and J]

4 minutes ago, JohnMo said:

Buying at full price, I would go Panasonic monobloc and just go to City Plumbing or Cylinder2Go (you get a discount )for the cylinder. Then you just need an UFH manifold.

 

Next job - do your pressure drop calculation assume a 100m long UFH loop and then use your pipe length to sort out primary feed pipe sizes. You want to be getting around 1.4m³/h flow rate (assuming 6kW), to keep UFH and cylinder happy.

Looking at 5kW as our heat loss at -2.3C is 2.5kW. (Does that mean I want to achieve 1.17m3/h flow rate or doesn’t it scale like that?).

 

I presume I need to calculate the number of linear 100m loops we need to calculate the full UFH flow resistance.  Again, I presume one dimensions Fiordland the UFH and simply assume the cylinder will be ok when the system switches over to DHW.

[JohnMo]

31 minutes ago, G and J said:

presume I need to calculate the number of linear 100m loops we need to calculate the full UFH flow resistance

No, as they are parallel loops, you just calculate the single longest (master loop).

[Iceverge]

3 hours ago, G and J said:

could go right by the front door

 

I doubt anyone would even notice it if you put one of these fancy covers over the top. 

 

3 hours ago, G and J said:

Or it could go near the road and impede a parking space

 

Mounted high on a wall? 

 

3 hours ago, G and J said:

In reality the sensible choice was to give up on an ASHP and fit a gas boiler, but, as a matter of principle, we wanted no gas.

 

One bill, no gas standing charge, no prospect of gas leaks, solar driven cooling. No need for a gas registered plumber to tinker if you need to. 

 

There's lots to like. 

 

Principles are good I suppose but be careful of dieing on any particular hill.

 

As someone who pours a chunk of concrete regularly, flies often, has lots of kids, farms beef and occasionally looses patience with stuff and sets it on fire in the yard, I'm all for principles.

 

Principles prevent environmentally savvy types drowning me in my own juices for the good of the planet. 

 

 

[G and J]

32 minutes ago, JohnMo said:

No, as they are parallel loops, you just calculate the single longest (master loop).

So not analogous to resistors in parallel then.   Hmmmm, yet more to learn. 

[G and J]

32 minutes ago, Iceverge said:

be careful of dieing on any particular hill

Was hoping for an extended dotage in a shallow hollow near a river and lots and lots of cafés.  But I take your point.

[Nickfromwales]

The extra length on the ASHP pipe 'could' be offset by bringing them indoors earlier, I guess, so they're in the heated envelope, but we're really down to a few brass tacks then and I'd rather not have the inconvenience of these pipes traversing the house interior tbh. Somethings gotta give!

 

I have, for a project in Graven Hill, run the ashp pipes through the slab insulation (atop the lower 100mm PIR slab, then capped by another 100mm layer, then 100mm polished concrete (with UFH & mesh)) so that the losses are minimised, as the delta between the pipes and their immediate surroundings are no longer so adverse. That could be possible for you without too much effort methinks; just use 2x28mm Hep2o runs and ditch the underground duo pipe then.