ASHP installed together with existing heating system

[Marvin]

Hi Bruno

 

I am sorry if you have already answered this question:

 

Do you have a valve that blends the hot water from your hot water tank with cold water to ensure that the water that comes out of your hot water taps is not too hot (scalding?)

 

Marvin

[Bruno]

  On 28/04/2021 at 18:13, Marvin said:

Do you have a valve that blends the hot water from your hot water tank with cold water to ensure that the water that comes out of your hot water taps is not too hot (scalding?)

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Yes, that was already installed with the DHW tank back when the original heating system (with the wood burner) was installed

[Bruno]

  On 28/04/2021 at 11:50, Nickfromwales said:

These for each of the 'feet' of the heat pump and go from there

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Going back to this, and using the picture I posted previously as a reference, I am not sure that I can lift the unit 20mm without extending the pipes. I just arrived home and went looking into that with more caution. 

I already have the rubber pads but I will wait for the installer to come and do that. I'm afraid that the "corners" which connect the pipes might get too much tension and break. That would be a real problem and I wouldn't be able to fix it myself. 

[Marvin]

 

Hi Bruno

 

I would especially insulate all the pipework, if possible, shown in RED inside and outside the building.

 

[Marvin]

Sorry, I meant this one.

 

[Nickfromwales]

  On 28/04/2021 at 18:30, Bruno said:

Going back to this, and using the picture I posted previously as a reference, I am not sure that I can lift the unit 20mm without extending the pipes. I just arrived home and went looking into that with more caution. 

I already have the rubber pads but I will wait for the installer to come and do that. I'm afraid that the "corners" which connect the pipes might get too much tension and break. That would be a real problem and I wouldn't be able to fix it myself. 

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Ask him to put flexible hoses from the unit as @dpmiller rightly pointed out. They will make a big difference. Make sure they’re suitable for the application though, eg full / large bore not the ones for hot and cold water which you won’t get a pencil through  

[Bruno]

  On 28/04/2021 at 18:36, Marvin said:

would especially insulate all the pipework, if possible, shown in RED inside and outside the building.

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On the inside I was already considering to insulate all pipes. I used in the past (previous plumbing from the wood burner) a kind of cardboard "pipe" filled with rock wool (sorry not sure if this is the correct term) around the pipes. That works very well, as I tested with a thermal camera before and after and the temperature around the pipes was greatly reduced. I'll post a picture later once I get to my archive

It's on the outside that I'm a bit lost, I have no idea what to use and how, in order to insulate and also to resist the weather. 

 

  On 28/04/2021 at 18:57, Nickfromwales said:

Ask him to put flexible hoses from the unit as @dpmiller rightly pointed out. They will make a big difference

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Will do for sure. Thank you 

[Marvin]

  On 28/04/2021 at 19:04, Bruno said:

On the inside I was already considering to insulate all pipes. I used in the past (previous plumbing from the wood burner) a kind of cardboard "pipe" filled with rock wool (sorry not sure if this is the correct term) around the pipes. That works very well, as I tested with a thermal camera before and after and the temperature around the pipes was greatly reduced. I'll post a picture later once I get to my archive

It's on the outside that I'm a bit lost, I have no idea what to use and how, in order to insulate and also to resist the weather. 

 

Will do for sure. Thank you 

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Hi Bruno.

 

Yes Rockwool really good. The thicker the wall the better especially outside. I use metal outside wrapping - see pictures.

 

Yes also resistance from UV and rain is a good idea for the pipes outside. 

 

Guess which ones are the hot ones??

 

 

[Marvin]

Hi Bruno

 

Sorry if I missed this but are there isolating valves on the pipework outside the building just before the wall mounted unit?

[Bruno]

No, there aren't. From the outside unit there are only pipes to the inside. All isolating valves are on the inside. 

[Marvin]

  On 28/04/2021 at 20:07, Bruno said:

No, there aren't. From the outside unit there are only pipes to the inside. All isolating valves are on the inside. 

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I'm not sure if this is right or wrong I was just looking at the Valliant layout showing 9r isolating valves before 10i the flexible pipes (flexible pipes to reduce vibration down pipes and to stop metal fatigue due to the vibrating of the unit).

 

Here's page 3 with the key:

 

[Bruno]

I did see that as well. The installer said that these are to be inside the house as someone could go and close them. 

Not a big deal there, just a few more liters of water to waste. And of course, to refill the heat pump and part of the circuit. 

 

I will install the flexible pipes for sure, then I'll install the rubber pads at the same time. 

[J1mbo]

  On 21/04/2021 at 23:27, Dan F said:

I've stil no idea what the "Heat Exchanger" is though or why you would use one.  It does seem, from looking at Vaillant schematics, that they only using glycol when there is a heat exchanger (seperate to any buffer tank) though..

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Glycol is antifreeze, the system should be protected based on local conditions. Eg in the Uk, to -18C.

 

The heat exchanger isolates the water in the radiator circuits from the water in the heat pump and cylinder coil. This means that the internal system can be worked on without having to refill glycol as only regular inhibitor and biocide are needed in the radiator circuit. This advantage is at the expense of a few K drop across the heat exchanger.

[Dan F]

  On 01/05/2021 at 06:12, J1mbo said:

Glycol is antifreeze, the system should be protected based on local conditions. Eg in the Uk, to -18C.

 

The heat exchanger isolates the water in the radiator circuits from the water in the heat pump and cylinder coil. This means that the internal system can be worked on without having to refill glycol as only regular inhibitor and biocide are needed in the radiator circuit. This advantage is at the expense of a few K drop across the heat exchanger.

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What set up do you have? 

- With/without hydraulic station.

- With/without heat exchanger.

- Vaillant buffer, third oart buffer or no buffer?

 

Our, yet to be installed design, has hydraulic station, generic 25l buffer vessel and no heat exchanger.  (Passivhaus with ground floor UFH only)

 

[Bruno]

Still looking into the flexible pipes, I need your help again. 

 

The flexible pipes shown in Vaillant installation videos for aroTHERM plus are just small connectors, nothing big. There is even an accessory kit which includes these connectors. 

Older arotherm manuals do mention a >0,75m flexible connection. 

 

The installer said that he cannot get these components (the flexible hoses/pipes) from Vaillant. Also, should I aim for the big pipes like in the older manuals, or the smaller ones as in recent documentation? 

Does anyone has a link for the 1 1/4" flexible hoses with 1 1/4" connection to the heat pump? On the wall we have 32mm pipes. 

[Bruno]

  On 28/04/2021 at 18:57, Nickfromwales said:

Ask him to put flexible hoses from the unit

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So a little update about this. Not me or the installer can get any references for these flexible hoses.

Meanwhile I was able to get in touch with Vaillant Portugal. I explained the problem with the noise/vibrations and asked them about these flexible hoses: why does aroTHERM plus has only a short flexible connection, while the "older" aroTHERM mentions clearly the >0,75m flexible connection. To my big surprise, they said that the current connection is fine and that these flexible hoses should not be necessary at all.

Thoughts?