Multipipe Maxima FM 16-port manifold (..and 13, 14, & 15)

[marshian]

Just now, mikeysoft said:

 

@marshian How do I fully insulate with 8 to 9cm build-up to play with?

Don’t bother at all

[mikeysoft]

1 minute ago, marshian said:

Don’t bother at all

 

Sorry, I don't understand.

[marshian]

Just now, mikeysoft said:

 

Sorry, I don't understand.

with 8-9 cm of build up to play with you can’t put the required level of insulation down.

 

so don’t put any down

 

did you watch the Urban Plumbers you tube I posted it explains why

[mikeysoft]

18 minutes ago, marshian said:

with 8-9 cm of build up to play with you can’t put the required level of insulation down.

 

so don’t put any down

 

did you watch the Urban Plumbers you tube I posted it explains why

 

OK I was replying to your "fully insulate", so it confused me when you then said don't bother at all.

 

I did watch it, and had watched a while ago along with his other videos.

 

So to help my understanding, why would heating our poorly insulated slab (100mm EPS under) directly, i.e. pipes on top of the slab, be much different to (apparently) heating it indirectly via pipes on top of 25mm PIR? The implication is you get the same system performance (same downward heat loss)?

 

Remembering that said 25mm PIR is already purchased and down, with a layer of DPM underneath, then DPM on top, and Profix PLUS panels affixed to the top slip sheet (plus PIR upstands around the edge of each room).

Edited July 29 by mikeysoft

[SteamyTea]

5 minutes ago, mikeysoft said:

 

So to help my understanding, why would heating our poorly insulated slab (100mm EPS under) directly, i.e. pipes on top of the slab, be much different to (apparently) heating it indirectly via pipes on top of 25mm PIR? The implication is you get the same system performance

Sum the R-Values of each component, assume a ∆K for each area, take the reciprocal of the result, calculate the hours of run times for each components per year, divide by 1000 and see what the differences are.

[Nickfromwales]

5 hours ago, mikeysoft said:

Remembering that said 25mm PIR is already purchased and down, with a layer of DPM underneath, then DPM on top, and Profix PLUS panels affixed to the top slip sheet (plus PIR upstands around the edge of each room)

I’ve scanned back through, and can’t find any mention of this. Have I missed you conveying this elsewhere?

 

If this is the case, then any other input is a waste of time, on floor build up etc, as you’re locked in to a solution you’re being told is weak/can be improved upon.

 

Is it a case of us remembering that, or that you’ve neglected to share the info? Happy to be corrected btw, happens more than once or twice as I’m  just a human being, but being told the horse has bolted is frustrating tbh.

 

5 hours ago, marshian said:

Don’t bother at all

👆

 

5 hours ago, mikeysoft said:

 

Sorry, I don't understand.

Previous comments have clearly stated to NOT decouple the heating from the slab, as the thin layer of insulation is pointless.

 

 

Same here, where I gas nailed the UFH pipes to a constructional slab, and then 65mm of liquid screed got pumped over it.

 

During the heating season this just sits there like a giant storage heater. Flow temp is about 3°C higher than target room temp.

 

The only thing that’s left to manipulate here is the pipe centres, and how many manifolds service the total area.

 

You mention 1st and 2nd floor heating is on the menu, perhaps we can stay ahead of that curve.

 

My 2 cents would be to put the loops in at 100mm centres to get as much water volume into the GF screed as is possible, and then dial back zones / loops after you’ve commissioned, according to the heat needed for each space.

[Andehh]

Always worth maintaining a focus on the payback period, and perspective. 

 

End of the day the UFH will work fine as OP has designed it, and for a large retrofit, the extra £30-50 (??) per month in heating costs for the heating season isn't a disaster vs spending 5 figures digging out a subfloor to increase the insulation.

 

OP has accepted the compromise, and I see his reasoning, as there is more to a design then raw efficiency. Buildhub is biased towards the raw efficiency to achieve top top 1% performance, but not everyone is as focused, and a top 15% performance vs average housing stock is fine for them! 

 

[Benpointer]

On 21/07/2025 at 23:03, Nickfromwales said:

...If nobody has a polished scrotum, don't invent a scrotum polisher  

 

 

 

Nobody knew they needed a smartphone until Steve Jobs came along with the iPhone...

 

Seriously though, I am interested in this conversation because my plumber suggests we should go for 16 loops to keep the pipe runs short (sub 100m).  He mentioned the Maxima FM from Multipipe (but just because he googled 16-port manifold).  

 

Whether we have 1 x 16 or 2 x 8-port, are we going to need an additional pump?  The Panasonic Aquarea L series we are getting has its own pump - I thought that would drive the UFH, am I wrong?  Thanks

 

[JohnMo]

1 minute ago, Benpointer said:

Panasonic Aquarea L series we are getting has its own pump - I thought that would drive the UFH, am I wrong?

But vague, you need to look at the specific model, as different sizes have different pumps.

 

Has the UFH been designed or thumb in air guess? With 16 loops the flow rate could be pretty high. So will need some thinking about.

 

What size is your floor?

[Benpointer]

6 minutes ago, JohnMo said:

But vague, you need to look at the specific model, as different sizes have different pumps.

 

Has the UFH been designed or thumb in air guess? With 16 loops the flow rate could be pretty high. So will need some thinking about.

 

What size is your floor?

Sorry, yes it's the 7kW Aquarea.  

 

Yes, it has been designed: Total floor area is 170m2, single storey, vaulted ceilings.  Room heat Watts/m2 from Heatpunk; planned flow temp = 35C; pipe spacing from my plumber using tables in an OFTEC manual...

 

(Hmmm... OFTEC are a 'liquid fuel trade association' - I might just check those pipe spacings against a quote I received from SoleHeat.)

[JohnMo]

I'm at 192m2, all vaulted loads of glass, did 7 loops, all works fine, your loss must be quite a bit higher, to need an 7kW heat pump as well. Are you a new build? If so are you sure you need that big a heat pump?

[JohnMo]

@Benpointer, just read your profile and the spec of your house. You should be near 2.5kW heating demand in Dorset. If so the 7kW Panasonic is huge, there smallest heat pump would be better suited?

[Benpointer]

1 hour ago, JohnMo said:

@Benpointer, just read your profile and the spec of your house. You should be near 2.5kW heating demand in Dorset. If so the 7kW Panasonic is huge, there smallest heat pump would be better suited?

Heatpunk may lie but that's what we've used. That gave a space heating demand of 4.3kW at -5C outside.  The BuildHub heat loss calculator gave only 2.7kW at -4C. 🤷‍♂️  We do also use a lot of hot water because we prefer baths to showers, so wanted to factor that in.  

 

Probably the 5kW would have been fine but there's £100 difference in price between the L-series 5kW and 7kW so, we played it safe. 

[JohnMo]

27 minutes ago, Benpointer said:

we played it safe

Going big isn't really playing it safe with heat pumps. You may need to add a volumiser to keep cycling in check.

[SimonD]

31 minutes ago, Benpointer said:

Heatpunk may lie but that's what we've used. That gave a space heating demand of 4.3kW at -5C outside.  The BuildHub heat loss calculator gave only 2.7kW at -4C. 🤷‍♂️  We do also use a lot of hot water because we prefer baths to showers, so wanted to factor that in.  

 

Probably the 5kW would have been fine but there's £100 difference in price between the L-series 5kW and 7kW so, we played it safe. 

 

I'd double check your figures and especially the assumptions in your project in Heatpunk. I'm just completing a trial of another design tool which came up with over 10kW on a property I'd calculated at under 7 in default mode.

 

I'm not a million miles from you and have a retrofit rather than newbuild which has ewi on existing walls and therefore only 0.21 u-value and some other compromises. Our house is larger than yours and we have 4.6kW losses. 

 

You really need to check the minimum output and compare it to your house w/k to understand demand at more average temperatures.

 

I think you're running the risk of lots of short cycling.

 

Also, is -5 really the design outdoor temperature for Devon?

Edited Sunday at 20:23 by SimonD

[Benpointer]

1 hour ago, SimonD said:

 

I'd double check your figures and especially the assumptions in your project in Heatpunk. I'm just completing a trial of another design tool which came up with over 10kW on a property I'd calculated at under 7 in default mode.

 

I'm not a million miles from you and have a retrofit rather than newbuild which has ewi on existing walls and therefore only 0.21 u-value and some other compromises. Our house is larger than yours and we have 4.6kW losses. 

 

You really need to check the minimum output and compare it to your house w/k to understand demand at more average temperatures.

 

I think you're running the risk of lots of short cycling.

 

Also, is -5 really the design outdoor temperature for Devon?

 

Firstly, in terms of re-thinking, that ship has already sailed - our heat pump is ordered and paid for.

 

Secondly, we've had Paul Thorney at Air2Heat review the design.  He instals a lot of Panasonic ASHPs and it was his recommendation to go for the 7kW rather than the 5kW.  He seems like a knowledgable trustworthy guy (certainly better than the local companies I spoke to, who although MCS registered, didn't seem to know their a*** from their elbow).  I doubt it made any financial difference to Paul if we went for the 5kW or the 7kW.  

 

@JohnMo The Panasonic kit includes a volumiser as standard anyway - primarily to facilitate defrost cycles.

 

If we've made a mistake, we'll live with it.  However, I think we'll be fine.  

 

[Nickfromwales]

11 minutes ago, Benpointer said:

primarily to facilitate defrost cycles.

If you avoid doing DHW pulls when it's the arse of winter (and use Off-peak > immersion instead) you can pretty much dodge the freezing/defrost issues.

 

A 7kW panasonic J series Aquerea I did in Oxford hasn't done one defrost since it was installed, service guy thought it was a fault, but we spoke and I confirmed my design 'ethos' and he said 'happy days'. Did a small LLH on that one as I had a pumped circuit going to the Brink Air Comfort AHU as well as flow to the UFH manifold.

[Benpointer]

3 minutes ago, Nickfromwales said:

If you avoid doing DHW pulls when it's the arse of winter (and use Off-peak > immersion instead) you can pretty much dodge the freezing/defrost issues.

 

A 7kW panasonic J series Aquerea I did in Oxford hasn't done one defrost since it was installed, service guy thought it was a fault, but we spoke and I confirmed my design 'ethos' and he said 'happy days'. Did a small LLH on that one as I had a pumped circuit going to the Brink Air Comfort AHU as well as flow to the UFH manifold.

I'd like to pretend that last paragraph made sense to me... but sadly it went way over my head 😂

[Nickfromwales]

2 minutes ago, Benpointer said:

I'd like to pretend that last paragraph made sense to me... but sadly it went way over my head 😂

A low loss header (LLH) is a mini buffer tank with 4 ports, vs a 2 port volumizer.

 

The AHU is a fan coil basically.

 

Better?

 

[dpmiller]

8 hours ago, Nickfromwales said:

If you avoid doing DHW pulls when it's the arse of winter (and use Off-peak > immersion instead) you can pretty much dodge the freezing/defrost issues.

yep. An hour of boost programmed into the immersion diverter means the ASHP can fill it's boots topping the slab up without pause.