Availability of combined A2A and A2W units in the UK

[dnb]

4 hours ago, PhilT said:

I notice some companies make a combined MVHR + heat pump of low capacity, presumably circulating warm air? Seems ideal in concept - what would prevent this from being a popular choice for a passivhaus?

I looked at one of these thinking it would make things a lot simpler (and therefore cheaper). It was anything but cheaper! The cost was nearly twice that of a Vent Axia MVHR unit and a Mitsubishi 6kW ducted airconditioner unit.  Then installation was actually not made much simpler for a larger cost because I couldn't just use my local contacts. All in all, the simplifications did not translate in to any form of reduced cost over the next 10 years.

 

It's never easy. But I tend to agree with @Iceverge and am following a similar strategy - 700W of oil filled radiator is keeping the chill off the new house nicely although we do have a bit bigger DHW requirement when we actually live there (not giving up the large bath!) and this is driving the requirements into an area where R290 might help if the price comes right.

[Iceverge]

@FelixtheHousecat

 

I completely get the desire to buy a package, heating, cooling and DHW from a single manufacturer. Mostly with the ideal that it'll all play ball and work well together. 

 

However you're putting all your eggs in one basket. 

 

A recent post here has a member looking at chucking an entire €15k GSHP system because a ground loop has burst. In my opinion you're better off to stick to standard components that can be easily swapped out and competitively sourced in future. 

 

 

 

 

 

 

[Joey]

6 hours ago, PhilT said:

I notice some companies make a combined MVHR + heat pump of low capacity, presumably circulating warm air? Seems ideal in concept - what would prevent this from being a popular choice for a passivhaus?

FWIW, I’ve recently looked into a couple of these from Total Home Environment after seeing them at the NSBRC. Our design isn’t passive, but it’s down at 15 W/m2 at -3 degrees, and they said a couple of options should work nicely.

 

First option was their smallest capacity unit, HPV1, for ventilation and heating, and HPW which is a 300L cylinder with a heat pump for DHW… £25,000 with basic options and another £6,000 if we wanted it installed. Another option was a Pichler unit called the PKOM4, which I think was actually slightly less powerful, but cost more. They also still recommend we’d probably want some extra heating capacity for extract only rooms and incase it gets really cold.
 

Shame, really liked the idea of the system. Not ruled out entirely, but we can basically get the same functionality from individual components for less.

[JohnMo]

8 hours ago, Joey said:

First option was their smallest capacity unit, HPV1, for ventilation and heating, and HPW which is a 300L cylinder with a heat pump for DHW… £25,000 with basic options and another £6,000 if we wanted it installed

And people pay or even think paying that? 

[Iceverge]

Its pretty bamboozling. 

 

I got a bit miffed with all the snake oil salesmen and just opted for the lowest capital investment I could. 

 

A plug in resistive heater and a direct 300l cylinder. Total upfront cost about €800 and a suck it and see approach for the rest.

 

Direct electric heating is expensive, even for a passive house (about €5/m2/yr) especially when you fall outside TOU tariffs which you will do without banking heat in a concrete slab or storage heater. 

 

Retrofitting anything is a pain too, I wish I'd been more proactive with ducting for example for an ASHP or putting a few more fuses spurs for a storage heater would have been very cheap. 

 

 

 

 

[Gone West]

9 hours ago, Joey said:

FWIW, I’ve recently looked into a couple of these from Total Home Environment after seeing them at the NSBRC.

I fitted a Genvex Combi 185LS back in 2017 and IIRC paid around £5000 buying it direct from Denmark. At the time it was around £8000 from Total Home Environment. The reason for buying it was that it's a compact unit offering MVHR, DHW and warm air heating and it worked well in our PH. The only downside was it had an enamelled steel DHW tank with an anode.

[SteamyTea]

25 minutes ago, Iceverge said:

putting a few more fuses spurs for a storage heater

This could be something that electricians recommend to people.

While I have a small house and very small loads, it is a shame that the E7 radial wiring (only 3 circuits) are in strange places to my mind (inside exterior walls next to the main sockets).

Couple of redundant circuits on a each floor would probably only cost £200 at time of build.  Now it would be many hundreds.

I suppose the biggest problem would be documenting them for future usage i.e. cable size and position.

[Iceverge]

1 hour ago, SteamyTea said:

This could be something that electricians recommend to people.

While I have a small house and very small loads, it is a shame that the E7 radial wiring (only 3 circuits) are in strange places to my mind (inside exterior walls next to the main sockets).

Couple of redundant circuits on a each floor would probably only cost £200 at time of build.  Now it would be many hundreds.

I suppose the biggest problem would be documenting them for future usage i.e. cable size and position.

 

As far as I know the specific circuits for TOU tarrifs are gone in Ireland. Not sure about the UK.  The whole house just goes to cheap leccy at certain times. A blanking plate over a prewired back box wouldn't be too intrusive in my mind. 

 

 

[SteamyTea]

6 minutes ago, Iceverge said:

A blanking plate over a prewired back box wouldn't be too intrusive in my mind. 

 

Yes, I could live with that.

6 minutes ago, Iceverge said:

As far as I know the specific circuits for TOU tarrifs are gone in Ireland. Not sure about the UK.

We seem to be getting more and more confusing ToU tariffs.

Will all end in tears before bedtime as most people can't even cope with E7.  Not helped by the power companies having different times for different places, then the clocks changing twice a year, but E7 is UTC all year.

 

Edited January 8 by SteamyTea

[Iceverge]

2 hours ago, Gone West said:

I fitted a Genvex Combi 185LS back in 2017 and IIRC paid around £5000 buying it direct from Denmark. At the time it was around £8000 from Total Home Environment. The reason for buying it was that it's a compact unit offering MVHR, DHW and warm air heating and it worked well in our PH. The only downside was it had an enamelled steel DHW tank with an anode.

 

That kind of cash would make it a much more attractive idea. 

 

At a rough guess for a 180m2 house. 

 

High quality MVHR unit ex ducting and manifolds. £2.5k

 

ESHP cylinder for DHW £2500k

 

A2A unit for space cooling+heating. £1000.

 

A bit of money saved because of avoiding a few different installers. Catching up on an old thread earlier I saw a Genvex unit had only failed after 25 years. 

 

It could persuade me for a passivhaus. 

[Joey]

1 hour ago, Iceverge said:

 

That kind of cash would make it a much more attractive idea. 

 

At a rough guess for a 180m2 house. 

 

High quality MVHR unit ex ducting and manifolds. £2.5k

 

ESHP cylinder for DHW £2500k

 

A2A unit for space cooling+heating. £1000.

 

A bit of money saved because of avoiding a few different installers. Catching up on an old thread earlier I saw a Genvex unit had only failed after 25 years. 

 

It could persuade me for a passivhaus. 

Haven’t come across that site before! After having a quick browse, it seems the Total Home Environment system they quoted £25k for is just a modified version of this with a fancy cover and couple of extra features… Sure this doesn’t include the water tank and ductwork, but it’s £21k less! Schematics and performance look almost identical.

 

[Gone West]

3 hours ago, Iceverge said:

At a rough guess for a 180m2 house. 

IIRC our house was only 120m2 for PHPP. I think unless the fabric of the building is significantly better than PH maximum levels, ie overall values U=0.1, the combi 185LS would struggle to keep the house warm. That is unless the interior is around 20C, but we did keep ours at 23C. That Plumbavent site is a good find, I'd have rather dealt with a UK company than Danish.