DIY-ish ASHP install

[vala]

So I got a quote for an ASHP install by a local heat geek installer and the price is way above what I can afford. After all the parts (at retail cost) it looked like it was £8000 of labour charge, for 10 man days. That matched up to their £120+VAT hourly rate.

I'm confident in getting it all plumbed in, and have near enough worked out the shopping list of parts but have a plumber on standby who said he'll help out especially with the bits that require paperwork. My go to sparkie will sort any electrical connections out.

One thing I was looking into using was a water distribution manifold after the DHW outlet and also one before the cylinder as I'll have a water softener fitted. The cold softened water would go to the cylinder and upstairs to the bathroom.

Is there any issues with using these as a means to provided distribution and isolation?

in particular with unvented cylinders?

[Chanmenie]

1 hour ago, vala said:

So I got a quote for an ASHP install by a local heat geek installer and the price is way above what I can afford. After all the parts (at retail cost) it looked like it was £8000 of labour charge, for 10 man days. That matched up to their £120+VAT hourly rate.

I'm confident in getting it all plumbed in, and have near enough worked out the shopping list of parts but have a plumber on standby who said he'll help out especially with the bits that require paperwork. My go to sparkie will sort any electrical connections out.

One thing I was looking into using was a water distribution manifold after the DHW outlet and also one before the cylinder as I'll have a water softener fitted. The cold softened water would go to the cylinder and upstairs to the bathroom.

Is there any issues with using these as a means to provided distribution and isolation?

in particular with unvented cylinders?

That’s a lot of money,  £120 an hour daylight robbery 

I’m not paying anywhere near that for my install.
I considered doing my own install, but as I’m only paying £1800 for having a Veismann Vitocal 151 installed why would I.

I suggest you get some more quotes 

[vala]

12 hours ago, Chanmenie said:

That’s a lot of money,  £120 an hour daylight robbery 

I’m not paying anywhere near that for my install.
I considered doing my own install, but as I’m only paying £1800 for having a Veismann Vitocal 151 installed why would I.

I suggest you get some more quotes 

The other quote I have is higher😳 for the equivalent Vaillant, and even higher for the Veissmann

They're both heat geek elites quoting and I think rather then deducting the BUS grant they're just adding it on.

I'm not fussed how they're pay structure is, how they run their business is up to them, and they do get work but for me it's just out of budget.

And another engineer I didn't get to the quote phase with as they wanted to add a number of zone valves/buffers/not run open loop etc which I dont want.

[SteamyTea]

13 hours ago, Chanmenie said:

 £120 an hour daylight robbery

I would happily work nights at that rate.

[Crofter]

AFAIK you only need someone with an f-gas cert to hook up the refrigerant lines. And you'll likely need a sparky to run a new circuit from the CU, unless you can run it as a spur off an existing circuit. I could be wrong about that. 

 

I'm hoping to go as DIY as possible with my A2A install, running the ducting etc myself.

[JamesPa]

18 minutes ago, Crofter said:

AFAIK you only need someone with an f-gas cert to hook up the refrigerant lines. And you'll likely need a sparky to run a new circuit from the CU, unless you can run it as a spur off an existing circuit. I could be wrong about that. 

 

I'm hoping to go as DIY as possible with my A2A install, running the ducting etc myself.

No refrigerant lines if you use a monobloc so no need for f-gas, but A2A does of course have refrigerant to connect up. 

Heat pumps typically take 16-32kW, so usually require a dedicated circuit, unless of course its a low capacity one.

[vala]

59 minutes ago, SteamyTea said:

I would happily work nights at that rate.

I couldn't believe it, but at the same time thought fair play.

If you can get the work at that rate why not.

47 minutes ago, Crofter said:

AFAIK you only need someone with an f-gas cert to hook up the refrigerant lines. And you'll likely need a sparky to run a new circuit from the CU, unless you can run it as a spur off an existing circuit. I could be wrong about that. 

 

I'm hoping to go as DIY as possible with my A2A install, running the ducting etc myself.

 

Yes. The consumer unit is under the stairs (where the cylinder/UFH manifold/ASHP controls will be) so the new circuit will be run from there.

26 minutes ago, JamesPa said:

No refrigerant lines if you use a monobloc so no need for f-gas, but A2A does of course have refrigerant to connect up. 

Heat pumps typically take 16-32kW, so usually require a dedicated circuit, unless of course it's a low capacity one.

I have had a heat loss survey completed by said installer. More so got this done to see if my own one (using heat engineer app) matched up and confirmed with the installer for a 5kW Arotherm Plus.

 

Can anyone confirm whether these water distribution manifolds would be ok to use?

[ProDave]

37 minutes ago, JamesPa said:

Heat pumps typically take 16-32kW, so usually require a dedicated circuit,

My 5kW ASHP draws a maximum input power of under 2kW so happy on a 16A circuit.

[JamesPa]

27 minutes ago, ProDave said:

My 5kW ASHP draws a maximum input power of under 2kW so happy on a 16A circuit.

 

Yes but wouldn't 16A  normally be a dedicated circuit (which was the question)? 

 

Having said that, 2kW is presumably OK off an otherwise lightly loaded ring (which many are) or even a 13A spur or a lightly loaded 20A radial.

 

I'm not sure if there are any rules requiring heat pumps to be on a dedicated circuit though and/or whether, even if there are not, some electricians/installers will nevertheless insist on one (obviously not relevant if you are self installing).  

 

Oh and in my most above 16-32kW should of course have read 16-32A!  Sorry about that.

Edited June 1 by JamesPa

[JohnMo]

1 hour ago, JamesPa said:

Heat pumps typically take 16-32kW

Just had a look at some data sheets, even a 14kW ASHP will only require a max of 6.6kW or 29 Amps

[JamesPa]

2 minutes ago, JohnMo said:

1 hour ago, JamesPa said:

Heat pumps typically take 16-32kW

Just had a look at some data sheets, even a 14kW ASHP will only require a max of 6.6kW or 29 Amps

Sorry mis-type.  I meant to say 16-32A!

Edited June 1 by JamesPa

[JohnMo]

4 minutes ago, JamesPa said:

not sure if there are any rules requiring heat pumps to be on a dedicated circuit though and/or whether, even if there are not, some electricians/installers will nevertheless insist on one (obviously not relevant if you are self installing

My manual says

 

Use a dedicated power line, do not power the appliance through a line to which other users are connected. 

[JamesPa]

9 minutes ago, JohnMo said:

My manual says

 

Use a dedicated power line, do not power the appliance through a line to which other users are connected. 

...which gets us back to the likelihood that the answer to the question posed (which was do I need a sparky to install a new circuit) is most likely yes in practice, even if technically it may be ok on an existing circuit.

 

That said, people wire single ovens into a ring main with no problem, similar load (to a heat pump of 6-7kW), albeit generally for shorter period of time.  I guess the 'diversity' argument doesn't really apply to a heat pump which can be on 24*7.  But if the only other appliances likely to be on the same ring are low wattage, what's the actual problem?  

Edited June 1 by JamesPa

[JohnMo]

16 hours ago, vala said:

One thing I was looking into using was a water distribution manifold after the DHW outlet and also one before the cylinder as I'll have a water softener fitted. The cold softened water would go to the cylinder and upstairs to the bathroom.

Is there any issues with using these as a means to provided distribution and isolation?

in particular with unvented cylinders?

Really to should take the cold water from the balanced feed on the inlet group for the UVC. But I did a retrofit so have a pressure control valve on the inlet to the house so in effect everything is balanced close enough as not to have issues).

 

No issues with a manifold. I have a manifold for hot and cold. One supply to each wet room and then branch from there. You would need two colds (one hard and the other soft water). Mine looks similar to the one shown but with a different makers name on it.

 

Are you new build or retrofitting?

[JohnMo]

53 minutes ago, vala said:

confirmed with the installer for a 5kW Arotherm Plus.

Or just about any other 6kW ASHP would do the job.  Don't be fooled in to buying very expensive ASHP most big manufacturers are just as good. As long as it's sized correctly and most importantly installed on a good system design all is good 

[vala]

With regards to the connection onto the CU I've got blank spaces so no issues with having a dedicated circuit. In fact the current oil combi is on its own circuit so I assume sparkie will just replace that.

 

@JohnMo My initial plan is from the cold feed into the house to tee off to the a manifold (for the fridge/hot water tap and heating circuit via the filling loop) and to the water softener. Then out of the softener it goes to another manifold which will go to the cylinder and to the bathroom.

Already got these manifolds in the bathroom as a means to have isolation as all the pipework is behind tiles. Done it all in plastic to not have any joins.

Sound ok?

[JohnMo]

Sound pretty similar to what I have (but no softener). Stop tap on bottom right, then outside tap, filter, prv, tee to cold manifold and the white pipe to cylinder. Top left comes from cylinder.

 

 

[vala]

@JohnMo perfect. thank you for confirming.

One thing I have noticed, but haven't paid much attention to till now, is that once the water mains comes into the house there's an adapter and its reduced to 15mm for the stopcock and so forth. I'm guessing that as I currently have a combi this isn't so much an issue, but going forward with an ASHP will this be.

Would it be wise to run from where it comes into the house in 22mm? Connection on most of the cylinders I've looked at appears to be 22mm for the cold water inlet and also the DHW.

I can always reduce down to 15mm, but I'm assuming sizing up isn't really a done thing?

[JohnMo]

3 minutes ago, vala said:

Would it be wise to run from where it comes into the house in 22mm?

I would convert to 22mm at the stop cock. Place hot water manifold close to cylinder and then run from there in 15mm Hep2O or similar to the wet rooms.

 

If you are not using the balanced cold water flow from the unvented cylinder inlet group, put a prv after the outside tap (if you have one or after the stop tap if you don't) that will ensure everything downstream is pretty much the same pressure for mixers etc. You will also need a check valve at the unvented cylinder hot water outlet to prevent any chances of reversing flow.

[vala]

34 minutes ago, JohnMo said:

I would convert to 22mm at the stop cock. Place hot water manifold close to cylinder and then run from there in 15mm Hep2O or similar to the wet rooms.

 

If you are not using the balanced cold water flow from the unvented cylinder inlet group, put a prv after the outside tap (if you have one or after the stop tap if you don't) that will ensure everything downstream is pretty much the same pressure for mixers etc. You will also need a check valve at the unvented cylinder hot water outlet to prevent any chances of reversing flow.

 

Can convert easily enough to 22mm so will get that done.

After the softener, and manifold, I'll go into the inlet control group then into the cylinder.

I could put a PRV before or straight after the softener so that the cold going to the bathroom, as well as what's feeding the cylinder is all the same pressure?

[eniacs]

I did mine DIY. Not sure id recommend it though, especially with the size of the grant as it is.

 

Surely you can find a cheaper installer, thats still good?

[G and J]

On 01/06/2024 at 15:32, vala said:

With regards to the connection onto the CU I've got blank spaces so no issues with having a dedicated circuit. In fact the current oil combi is on its own circuit so I assume sparkie will just replace that.

 

@JohnMo My initial plan is from the cold feed into the house to tee off to the a manifold (for the fridge/hot water tap and heating circuit via the filling loop) and to the water softener. Then out of the softener it goes to another manifold which will go to the cylinder and to the bathroom.

Already got these manifolds in the bathroom as a means to have isolation as all the pipework is behind tiles. Done it all in plastic to not have any joins.

Sound ok?

Maybe too off topic but is a non softened feed needed with modern softeners?   I was told recently that current designs mean softened water is safe to drink?

[JohnMo]

33 minutes ago, G and J said:

I was told recently that current designs mean softened water is safe to drink

Still tastes rubbish and if salt based there can be issues with salt content.

 

But you could always just use a Poly Phosphate based cartridge system like a BWT combi care. Just put it in the fed to the UVC (22mm). Change cartridge every 12 months. Not a softener as such just stops or reduces scale buildup by stopping the process.

 

A simple explanation here

 

https://silksoftwater.com/water-treatment/water-conditioner/polyphosphates-in-hard-water-treatment/

 

[sharpener]

Personally, having experience of both very hard and very soft water supplies I would only want softened water in the shower; the loos, dishwasher and washing m/c do not really need it.

 

AFAIK ion-exchange softeners still work by replacing the calcium (and magnesium) ions with sodium, which will increase your blood pressure if you drink a lot of it. The kind which allegedly use magnets etc to change the structure of the molecules in the water are unlikely to do this.

 

Polyphosphates are widely used by water authorities, orginally to prevent lead being leached out of lead pipes. I was told they do this even where the hard water means it doesn't actually happen anyway. But it does cause an annoying scum to form on tea and coffee.

 

I wonder if ion exchange softening also changes the pH of the water or is otherwise bad for heat pumps? Naturally soft water is often quite acid. Harvested rain water is AFAIR pH 5.3 bc of CO2 dissolved from the atmosphere, I have some trouble neutralising the acidity and won't be using it to fill my heating system. SWW use sodium hydroxide to raise the pH so that introduces some sodium too.

 

Vaillant have some quite detailed specifications in their HP installation instructions (though the footnotes refer to boilers where scaling is much more of a problem), I wonder how many installers follow them? pH 8.2 is quite alkaline (the lower limit for potable water in the UK is 6.5), you would need to add >100g of sodium bicarbonate per cu m to achieve that.