How can I put air con onto a mvhr ductwork?

[Petrochemicals]

Hello, 

 

I finally have put a Mvhr on the house, I have been looking for years, I have read quite a bit of this forum, but I cannot find how to put an aircon onto to the ductwork. 

 

There are heating and cooling coils that have been mentioned on the forum, they seem to be in association with heat pumps of one description or another. 

[Dave Jones]

we are using the Zehnder CW6, not fitted yet so cant give you any feedback.

 

https://products.zehnder.co.uk/en/product/zehnder-cw6

 

 

[Nickfromwales]

47 minutes ago, Petrochemicals said:

Hello, 

 

I finally have put a Mvhr on the house, I have been looking for years, I have read quite a bit of this forum, but I cannot find how to put an aircon onto to the ductwork. 

 

There are heating and cooling coils that have been mentioned on the forum, they seem to be in association with heat pumps of one description or another. 

Have you insulated the ductwork supplying air to the rooms?

Do you understand the difference between air con and cooling too? Just before we get 'into it'  

[SteamyTea]

58 minutes ago, Nickfromwales said:

Do you understand the difference between air con and cooling too? Just before we get 'into it'

Was my first thought.

My car has both. One involves opening the window.

[JohnMo]

5 hours ago, Petrochemicals said:

cannot find how to put an aircon onto to the ductwork

Maybe there's a good reason you cannot find anything, as they are two different independent systems.

 

MVHR does around 0.5 ACH, so cannot carry enough flow to effectively cool the house, in heating mode, a passivhaus is designed around the max achievable heat flow through the ventilation system that being 10W/m2.

 

The flow figures for Aircon are something like 47.0 - 60.5 L/S per kW of cooling capacity.  That's about the same flow rate for our MVHR for near 200m2 house.  So MVHR would be able to carry about 1kWh for our house, which would be rubbish and not worth the effort.

 

If you want Aircon, get an Aircon unit or consider floor cooling etc.

 

 

[Petrochemicals]

7 hours ago, Nickfromwales said:

Have you insulated the ductwork supplying air to the rooms?

Do you understand the difference between air con and cooling too? Just before we get 'into it'  

Well I have only just joined, and 2 rude replies, are you the local moron? 

[Petrochemicals]

8 hours ago, Dave Jones said:

we are using the Zehnder CW6, not fitted yet so cant give you any feedback.

 

https://products.zehnder.co.uk/en/product/zehnder-cw6

 

 

This is off an air to water heat pump, not a refrigerant gas type.  Where do I get a cool water air con. 

[Kelvin]

6 minutes ago, Petrochemicals said:

Well I have only just joined, and 2 rude replies, are you the local moron? 

He’s one of the most helpful and knowledgeable people on here. I suggest you spend more time reading the forum to get a feel for the members and how and what they post. 

[Petrochemicals]

2 hours ago, JohnMo said:

Maybe there's a good reason you cannot find anything, as they are two different independent systems.

 

MVHR does around 0.5 ACH, so cannot carry enough flow to effectively cool the house, in heating mode, a passivhaus is designed around the max achievable heat flow through the ventilation system that being 10W/m2.

 

The flow figures for Aircon are something like 47.0 - 60.5 L/S per kW of cooling capacity.  That's about the same flow rate for our MVHR for near 200m2 house.  So MVHR would be able to carry about 1kWh for our house, which would be rubbish and not worth the effort.

 

If you want Aircon, get an Aircon unit or consider floor cooling etc.

 

 

Yes, I have been made aware of this, I have a unit that does 500 m3 per hour,  or 500,000 litres, or 138l per second. By your figures that's about a 2.5kwh, which is a small ac unit. 

 

By use of a portable ac and sunshades my house was a nice 22C during the 39 degree heatwave. 

[Petrochemicals]

4 minutes ago, Kelvin said:

He’s one of the most helpful and knowledgeable people on here. I suggest you spend more time reading the forum to get a feel for the members and how and what they post. 

And you are one of the brownest noses. In what way does his reply justify your reply?

 

If you wish to ban me and keep this as "your Club" feel free, but I am not here to press the flesh. 

[crispy_wafer]

TBH, I'd ask the manufacturer, or system supplier/designer what they'd recommend for your particular install.

 

Check the ducting aswell, otherwise you may have an issue with condensation.

[Beechgate]

Kelvin is right.

 

If you're looking to tap the knowledge on this forum perhaps chalk this up as a bad start and rethink your approach

[Kelvin]

38 minutes ago, Petrochemicals said:

And you are one of the brownest noses. In what way does his reply justify your reply?

 

If you wish to ban me and keep this as "your Club" feel free, but I am not here to press the flesh. 

No one wishes to ban you. I’m just giving you some friendly advice on the best way to approach a new forum.
 

Edited March 10, 2023 by Kelvin

[Andehh]

Yikes, that escalated quick! 

 

OP, chill out... Geddit? (I'm joking) The locals speak the truth, if you want to cool properly stick to dedicated AC, MVHR is just to light and slow to make a meaningful difference. 

 

I looked into it before shitting myself into an extra £4k to install proper AC. 

[PeterW]

You can’t do air conditioning with MVHR due to flow volume, you can do basic warming and cooling of the airflow using a water duct battery but it’s going to add / remove 5-800w at most. You’ll also find that MVHR duct is only 30% of the size of standard AC duct so you won’t get significant airflow without a lot of noise.

The second issue is that you have to ensure the whole system is cooling ready if you drop the air temp low enough you will end up with condensation external to the ductwork which will cause damp issues.

 

Secondary ducting is needed to do AC correctly if you don’t want to use wall units or ceiling cassettes - you can then use a ducted battery but these need minimum 125mm duct so that needs a lot of planning. 
 

 

[Petrochemicals]

 

13 minutes ago, PeterW said:

You can’t do air conditioning with MVHR due to flow volume, you can do basic warming and cooling of the airflow using a water duct battery but it’s going to add / remove 5-800w at most. You’ll also find that MVHR duct is only 30% of the size of standard AC duct so you won’t get significant airflow without a lot of noise.

The second issue is that you have to ensure the whole system is cooling ready if you drop the air temp low enough you will end up with condensation external to the ductwork which will cause damp issues.

 

Secondary ducting is needed to do AC correctly if you don’t want to use wall units or ceiling cassettes - you can then use a ducted battery but these need minimum 125mm duct so that needs a lot of planning. 
 

 

To be perfectly honest I'm willing to give it a go, the noise is acceptable during the day for those few days, obviously it would have to go off at night which is not ideal, but the portable one I have at present has to go off at night because of the noise, it works by swallowing inside air, spitting half out hot to the outside and half out cold to the inside, thus meaning you are drawing air in from the outside anyway. 

 

The pipes are insulated all the way to the outside, condensation isn't an issue for a few days anyway, especially when the loft will be somewhere around 35c. 

[Petrochemicals]

52 minutes ago, Andehh said:

Yikes, that escalated quick! 

 

OP, chill out... Geddit? (I'm joking) The locals speak the truth, if you want to cool properly stick to dedicated AC, MVHR is just to light and slow to make a meaningful difference. 

 

I looked into it before shitting myself into an extra £4k to install proper AC. 

You can get split units with 4 wall units for about a grand but now the ducts are in I would quite like to use them. 

[Petrochemicals]

1 hour ago, crispy_wafer said:

TBH, I'd ask the manufacturer, or system supplier/designer what they'd recommend for your particular install.

 

Check the ducting aswell, otherwise you may have an issue with condensation.

For a heatwave of a few days a year  I cannot really see condensation being a major problem, plus once it leaves the chiller bit it is only going to get warmer, condensation on the outside but in the temperature and relative humidity it will be it will quickly dissappear. 

 

The bacteria et al build up takes time, wood gets wet but as it dries the bacteria dissappear, thus meaning the wood does not rot, the problem is wood that is consistently above 20 percent water, most wood is above 10 percent water at any time. 

[Nickfromwales]

15 hours ago, Petrochemicals said:

Well I have only just joined, and 2 rude replies, are you the local moron? 

Not that I care to waste any of my valuable personal time responding to such a nonsense response, but what exactly do you consider "rude".

I asked you two very simple questions, and, if you want help, maybe you should read between the lines and answer them so you can receive said help.

 

Folk on here reply to help people for free, on a forum which is free to join, so, IF you wish to jump down, momentarily, off the highest horse I've seen for quite some time, I would be happy to answer you questions.

 

For definition;

A "moron" would install a system which was not properly designed and installed as fit for purpose, so if I was the kind of person to make any assumptions or be "rude" to you, my question in my first reply would have read "What MORON designed this system where they didn't define the parameters or install it fit for purpose?", and then, referring to someone as a moron would be fine and appropriate. 👍 For further clarity, I am NOT referring to you as the moron, yet, as I do not know if you were said moron or not. Once I have ascertained who the moron actually is, then I will engage, with all of my many years of dealing with morons, my retort.

 

 Usage of Moron

 

The terms idiot, imbecile, moron, and their derivatives were formerly used as technical descriptors in medical, educational, and regulatory contexts. These uses were broadly rejected by the close of the 20th century and are now considered offensive.

 

As we like to offer comprehensive replies here at Buildhub, please be aware that, rather embarrassingly, your attempt to insult me is actually about a century out of date. You may need to go to another forum to get some up to date material. 

 

OK, so lets assume you did come here fore free help, I will rephrase my questions to you as follows.

 

22 hours ago, Nickfromwales said:

Have you insulated the ductwork supplying air to the rooms?

Do you understand the difference between air con and cooling too? 

 

Should have read;

Please could you tell me if the already installed ductwork has been insulated?

Are you aware that there is a huge difference between air con and cooling?

 

There you go, and hopefully this makes up for me upsetting you so much by trying to help you, for free, in my spare time. Please also be aware, that If you can't get a reasonably speedy and satisfactory answer here, then please go and employ a system designer, who will take money from you in return for the answers you seek.

 

Kind regards, Nick.

[Mr Punter]

ChatGPT:

 

Installing air conditioning onto a Mechanical Ventilation with Heat Recovery (MVHR) ductwork system can be a bit complicated, and it's usually best to consult a professional HVAC technician or engineer for proper installation.

However, here are some general steps that may be involved in putting air con onto an MVHR ductwork:

1. Determine the appropriate size and type of air conditioning system needed for your space, taking into account factors such as room size, insulation, and desired temperature range.

2. Assess the existing ductwork system to see if it's compatible with the air conditioning system you plan to install. If the ductwork is too small or poorly designed, it may need to be modified or replaced to ensure proper airflow and ventilation.

3. Install the air conditioning unit near the MVHR unit, ideally on the supply air side of the ductwork system. This will allow the air to be cooled before it enters the living space.

4. Connect the air conditioning unit to the ductwork system using appropriate connectors and fittings. Make sure the connections are sealed properly to prevent air leaks.

5. Install any necessary controls and sensors, such as a thermostat or temperature sensor, to ensure proper operation and regulation of the air conditioning system.

6. Test the system to ensure it's functioning properly and delivering the desired temperature and air flow. Adjust settings as needed to optimize performance and efficiency.

Again, it's important to note that installing air conditioning onto an MVHR ductwork system can be complex and may require professional assistance. Improper installation or modification of the system could result in reduced efficiency, increased energy costs, and even safety hazards.

[Nickfromwales]

17 hours ago, Petrochemicals said:

And you are one of the brownest noses. In what way does his reply justify your reply?

 

If you wish to ban me and keep this as "your Club" feel free, but I am not here to press the flesh. 

As you have technically not yet broken any of the rules of this forum, we can't really ban you. Plus, have you ever heard the phrase "give them enough rope"?

 

Also, this is just pure gold, keep them coming. 😆 I've not laughed this much since Auntie Mabel caught her left tit in the mangle.

 

18 hours ago, Kelvin said:

He’s one of the most helpful and knowledgeable people on here. I suggest you spend more time reading the forum to get a feel for the members and how and what they post. 

@Kelvin

Could I please refer you to the T's & C's, section 69, item 69, subsection 6-9, where it clearly states "thou shalthst ( spelt correctly, I checked ) not engage-eth in the medieval act of the browning of the nose". This is a grandfather clause, often overlooked, so if you wish to avoid a permanent ban from Buildhub I urge to to take all of today, and 37.4592% of Sunday ( not this Sunday, but the one after next, and I'll be checking ) to properly familiarise yourself with our policies.

 

I expected better of you tbh. 🙄    

 

[Nickfromwales]

12 hours ago, Petrochemicals said:

The pipes are insulated all the way to the outside, condensation isn't an issue for a few days anyway, especially when the loft will be somewhere around 35c. 

 

2 minutes ago, Nickfromwales said:

this is just pure gold

Google 'delta T', and get a reality check on where the dew-point would be.

 

I'm not sure what books you've been reading and researching from, but I'd avoid the fiction section from now on. 

[Kelvin]

28 minutes ago, Nickfromwales said:

As you have technically not yet broken any of the rules of this forum, we can't really ban you. Plus, have you ever heard the phrase "give them enough rope"?

 

Also, this is just pure gold, keep them coming. 😆 I've not laughed this much since Auntie Mabel caught her left tit in the mangle.

 

@Kelvin

Could I please refer you to the T's & C's, section 69, item 69, subsection 6-9, where it clearly states "thou shalthst ( spelt correctly, I checked ) not engage-eth in the medieval act of the browning of the nose". This is a grandfather clause, often overlooked, so if you wish to avoid a permanent ban from Buildhub I urge to to take all of today, and 37.4592% of Sunday ( not this Sunday, but the one after next, and I'll be checking ) to properly familiarise yourself with out policies.

 

I expected better of you tbh. 🙄    

 

Duly noted. I shall stand naked on my foundation in the freezing cold admiring my very neat over complicated ducting 

[Nickfromwales]

12 minutes ago, Kelvin said:

Duly noted. I shall stand naked on my foundation in the freezing cold

Good lad. We will  not, of course, accept your word for it. Please post photos here for "authentication". We will make allowances for it being cold when we score you.  

15 minutes ago, Kelvin said:

my very neat over complicated ducting 

Don't forget to insulate them. You never know when you'll need to add "air con" ( not cooling ) from an A2W HP

[PeterW]

17 minutes ago, Kelvin said:

Duly noted. I shall stand naked on my foundation in the freezing cold admiring my very neat over complicated ducting 

If it is very cold you may find your ducting has contracted to the point that it’s barely visible …