ASHP location

[kandgmitchell]

Right from planning stage I had allowed for the ASHP unit to stand against the side of the house near the front corner. Now in the throes of organising the foundation design I see the location of the ASHP base will impinge on the required safety zone around the Vaillant Arotherm due to the position of the side door. I have now slid the location of the base further to the front which means the fan unit will protrude about half it's length past the front wall. 

 

This installation is part of the house package and their designers have raised a concern that the unit will be exposed and not function as well as one fully against a wall. Their suggestion is to put it against the front wall. Well they can tell my wife that, I'm certainly not! Vaillant suggest the unit can be remotely sited or placed on a flat roof so I can't see the problem.

 

Is there a problem? If there is I'll come up with a screen for the height of the unit.

[ProDave]

This is more likely going to be a planning issue if it is in front of the house.  Care to post a plan showing old and new location?

[kandgmitchell]

Good point - another arguement to not have it on the front. Here's my suggested revised position. The original (shown within the planning application) was where the down pipe and tap now are, i.e alongside the door.

heat pump sketch.pdf

[ProDave]

Can you explain the drawing?  There is a rectangle box and an L shaped box, joined together by a red dotted rectangle.    If one is the original and the other the modified position why the different shapes?  If there are two outside boxes what are they?

 

In any event I seen no harm in moving it / they back to the L shaped one is in line with the front of the building.

[kandgmitchell]

Ah, the red dotted line is the external unit, the black boxes are the concrete support pads (the L shaped one contains the pipe duct). This is the proposed position with the correct 1.0m clearance to the side door.

[ProDave]

Thanks for the clarification.

 

Frankly I would just move it back a touch so the front edge of the unit is in line with the front of the house.

 

So the back edge will be less than 1 metre from the back door.  What practical problem is that going to create?  Who is going to notice let alone measure it?

[kandgmitchell]

Vaillant have an installation requirement that the unit should be a minimum of 1.0m from openings into the building in case ofthe escape of the gas used in the unit. The installer isn't going to ignore that I'm afraid as it was they who raised it.

 

It's more about their concern that wind passing through the unit reduces it's efficiency that I need. Is it a thing?

[JohnMo]

37 minutes ago, kandgmitchell said:

more about their concern that wind passing through the unit reduces it's efficiency that I need. Is it a thing?

The heat pump will be makings air pass through itself when online, the air will be ambient, so would any wind. It's an inanimate object, not affected by wind chill, as humans are.

[ProDave]

5 minutes ago, JohnMo said:

The heat pump will be makings air pass through itself when online, the air will be ambient, so would any wind. It's an inanimate object, not affected by wind chill, as humans are.

But if you rotate it 90 degrees from how it is shown with the front in line with the house I bet it will meet the 1 metre from the door opening.

 

They draw ambient air in the back and cooled air gets expelled from the front, so site the front facing the road and the cold air will blow that way not towards your door.

 

Alternatively, if they insist on that orientation, then surely the 1M would be measured in a straight line from the corner of the door opening, to the nearest corner of the ASHP.  So how much further out from the building would it need to be for the front edge to be in line with the front of the wall and the 1M distance achieved.

 

Cut a large piece of cardboard or plywood or whatever you have around to the size of the ASHP and go and try it on the ground.

[sharpener]

3 hours ago, ProDave said:

But if you rotate it 90 degrees from how it is shown with the front in line with the house I bet it will meet the 1 metre from the door opening.

 

They draw ambient air in the back and cooled air gets expelled from the front, so site the front facing the road and the cold air will blow that way not towards your door.

 

Alternatively, if they insist on that orientation, then surely the 1M would be measured in a straight line from the corner of the door opening, to the nearest corner of the ASHP.  So how much further out from the building would it need to be for the front edge to be in line with the front of the wall and the 1M distance achieved.

 

Cut a large piece of cardboard or plywood or whatever you have around to the size of the ASHP and go and try it on the ground.

 

This is the actual spec:

[ProDave]

I see.  R290 is a posh name for Propane gas.  Propane is heavier than air so they don't want a leak filling up drains, getting into buildings etc.

 

Is is possible to swap to an ASHP using something other than R290?

[MikeGrahamT21]

29 minutes ago, ProDave said:

I see.  R290 is a posh name for Propane gas.  Propane is heavier than air so they don't want a leak filling up drains, getting into buildings etc.

 

Is is possible to swap to an ASHP using something other than R290?

R290 is indeed propane, I read that it’s a super pure version of propane and extremely flammable which is why they don’t use it in car air conditioning 

[sharpener]

On 02/11/2023 at 15:19, ProDave said:

I see.  R290 is a posh name for Propane gas.  Propane is heavier than air so they don't want a leak filling up drains, getting into buildings etc.

 

Is is possible to swap to an ASHP using something other than R290?

 

Well yes, there are still lots of machines on the market that use R32. But R290 gives you higher flow temperatures and higher CoP for any given temperature so it is the way to go. As the amounts of refrigerant are tiny (and you are allowed to have bottled or piped propane in the house for cooking) I think the dangers are exaggerated, but I can see that no-one would want to install in a non-compliant fashion.

 

I think the caution stems from the fact that many German houses have cellars/basements where it could accumulate to dangerous levels.

[ProDave]

1 hour ago, sharpener said:

As the amounts of refrigerant are tiny (and you are allowed to have bottled or piped propane in the house for cooking) I think the dangers are exaggerated, but I can see that no-one would want to install in a non-compliant fashion.

If you have bottled LPG you will find a very similar set of restrictions on where you are allowed to site the bottles in relation to drains, air bricks, or other openings, opening windows and doors etc.  For all the same reasons, to prevent escaping gas entering the building.

[JohnMo]

11 hours ago, sharpener said:

think the dangers are exaggerated,

A gas explosion

https://www.yachtingmonthly.com/sailing-skills/crash-test-boat-gas-explosion-29779

 

A Vaillant ASHP has around 0.6kg of R290, so a volume in a liquid state of 1.2L, however in the gaseous state it expands, that increases the volume to 320L. A leak in the high pressure circuit would result in a big instantaneous pressure drop and any liquid would convert to gas and freely mix with any oxygen. Then you just need an ignition source.

 

So not sure the dangers are that exaggerated. Would certainly lead to more than a bad hair day, if things did go wrong.

Edited November 4, 2023 by JohnMo

[PhilT]

All sources I can find say R32 has a higher overall coefficient of performance than R290. One source quotes 87% better. Some sources say R290 is better at very low temps but in Sweden, according to a report by the Swedish Energy Agency, R32 still accounted for 60% of all heat pump sales in 2022 whereas R290 accounted for only 10% of sales.

[JohnMo]

56 minutes ago, PhilT said:

All sources I can find say R32 has a higher overall coefficient of performance than R290. One source quotes 87% better. Some sources say R290 is better at very low temps but in Sweden, according to a report by the Swedish Energy Agency, R32 still accounted for 60% of all heat pump sales in 2022 whereas R290 accounted for only 10% of sales.

Bigger difference in performance is obtained by good design of the system it's connected into. Everything that is different is small percentage points, but a R290 does give a much higher ASHP output temperature if that is important to you - 75 compared to 60.

 

 

[PhilT]

1 hour ago, JohnMo said:

Bigger difference in performance is obtained by good design of the system it's connected into. Everything that is different is small percentage points, but a R290 does give a much higher ASHP output temperature if that is important to you - 75 compared to 60.

 

 

does anyone use Bard? It suits a lazy git like me from having to wade through tons of confusing google sources...

 

R32 is capable of higher heat pump flow temperature than R290. R32 has a maximum flow temperature of 65°C, while R290 has a maximum flow temperature of 60°C. This is because R32 has a higher critical temperature than R290.

Critical temperature is the temperature above which a gas cannot be liquefied by increasing the pressure. A higher critical temperature means that a refrigerant can be used at higher temperatures.

R32 is also a more efficient refrigerant than R290 at higher temperatures. This is because R32 has a higher latent heat of vaporization. Latent heat of vaporization is the amount of energy required to convert a liquid to a gas at a constant temperature. A higher latent heat of vaporization means that a refrigerant can absorb more heat from the surrounding environment.

In general, R32 is a good choice for heat pumps that need to supply hot water at high temperatures, such as for radiant heating systems. R290 is a good choice for heat pumps that need to supply hot water at medium temperatures, such as for domestic hot water systems.

However, it is important to note that R290 is a flammable refrigerant, while R32 is a mildly flammable refrigerant. This means that R290 heat pumps must be installed and serviced by qualified professionals.

 

Is it right though?

Edited November 4, 2023 by PhilT

[JohnMo]

Vaillant R290 is capable of 75 degs, my R32 is only capable of 60 degs. That could be down to a bigger plate exchanger or the refrigerant?

 

Nearly all ASHP are monobloc so no one is touching or exposing the refrigerant so both the same. R32 is an F gas, so only qualified people can use or fill systems, such as split systems, R290 is not an F gas but flammable.

[Beelbeebub]

2 hours ago, PhilT said:

does anyone use Bard? It suits a lazy git like me from having to wade through tons of confusing google sources...

 

R32 is capable of higher heat pump flow temperature than R290. R32 has a maximum flow temperature of 65°C, while R290 has a maximum flow temperature of 60°C. This is because R32 has a higher critical temperature than R290.

Critical temperature is the temperature above which a gas cannot be liquefied by increasing the pressure. A higher critical temperature means that a refrigerant can be used at higher temperatures.

R32 is also a more efficient refrigerant than R290 at higher temperatures. This is because R32 has a higher latent heat of vaporization. Latent heat of vaporization is the amount of energy required to convert a liquid to a gas at a constant temperature. A higher latent heat of vaporization means that a refrigerant can absorb more heat from the surrounding environment.

In general, R32 is a good choice for heat pumps that need to supply hot water at high temperatures, such as for radiant heating systems. R290 is a good choice for heat pumps that need to supply hot water at medium temperatures, such as for domestic hot water systems.

However, it is important to note that R290 is a flammable refrigerant, while R32 is a mildly flammable refrigerant. This means that R290 heat pumps must be installed and serviced by qualified professionals.

 

Is it right though?

The problem with bard and other chatbots is they produce something that sounds plausible but is not necessarily true.

 

So if you feed it a bunch of inputs from sales brochures it will simply come up with something that could plausibly be a sales brochure for heatpumps.

 

Little things like the accuracy of numbers quoted are less important than numbers being quoted.

 

All things being equal, R290 can achieve higher water temps than r32 and operate at lower external temps. The efficiencies are similar with system design being more important than the refrigerant. 

 

The downside of r290 is it's very flammable, whilst r32 is only mildly. R290 needs special attention to what could happen if it leaks from a fire/explosion perspective. R32 much less so.

 

The downside of r32 is it has a global warming potential in the many hundreds (better than told stuff that was in the thousands tho). If you let the r32 escape from a typical monobloc it it the equivalent of about 1t of co2. R290 has negligible GWP. The r290 from a typical heatpump is equivalent to a few kg of co2.

 

 

[S2D2]

5 hours ago, PhilT said:

Is it right though?

No. 

[JohnMo]

5 hours ago, PhilT said:

does anyone use Bard? It suits a lazy git like me from having to wade through tons of confusing google sources...

Artificial intelligence 0,

Hard work checking through loads of shite on the internet and doing due diligence 1

[PhilT]

6 minutes ago, S2D2 said:

No. 

Stretching the OP a bit but it is still relevant if location for an R290 is critical.

 

The very first research paper I could find says this, maybe others say differently It may be worth finding out.

 

2016 - Performance Comparison of R32, R410A and R290 Refrigerant in Inverter Heat Pumps Application

(extract from abstract)

"From the results, R32 has better heating performance 6% for BTW and 12% in ATW application when compared with both R410A and R-290. Consider to the refrigerant properties, the changing of R410A to R32 can keep compressors stoke volume. Meanwhile 57% stoke volume increasing of R290 must be implemented to keep the same capacity level, Consequently R32 is the candidate refrigerant for heat pump application when DSH control has been applied"

 

[Beelbeebub]

8 minutes ago, PhilT said:

Stretching the OP a bit but it is still relevant if location for an R290 is critical.

 

The very first research paper I could find says this, maybe others say differently It may be worth finding out.

 

2016 - Performance Comparison of R32, R410A and R290 Refrigerant in Inverter Heat Pumps Application

(extract from abstract)

"From the results, R32 has better heating performance 6% for BTW and 12% in ATW application when compared with both R410A and R-290. Consider to the refrigerant properties, the changing of R410A to R32 can keep compressors stoke volume. Meanwhile 57% stoke volume increasing of R290 must be implemented to keep the same capacity level, Consequently R32 is the candidate refrigerant for heat pump application when DSH control has been applied"

 

I think that paper was looking at using the same physical equipment but swapping fluids.

 

It is relevent because a chunk of the market is retrofitting older units with newer refrigerants. So effort has gone into working out which new refidgerant to use in a given set of circumstances.

 

As they point out the compressor specs for r290 differ from those of a similarly spec'd r410a unit. R32 is a better "drop in" than r290

 

But when it comes to a unit designed for r290's properties i think the picture is different.

 

Efficiency wise similar, but with wider operating range, higher max temps.