Do I Need To Upgrade My Pipework For A Heat Pump Install? | Consumer Advice

For 6kw heat pomp,what pipe size i need?

Great video. Used your info to do some checks that the installers putting an ASHP in for me this coming week are not taking shortcuts.

I'm struggling to get my 8.5 kw eco dan above a scop of 2.6

Hi Adam, interesting. Could you give an indication of the % efficiency reduction of a heat pump working with a temperature difference of 6 degrees versus 5 degrees? I live in the Netherlands, no heat geeks here.

O no I just did a new build in 22mm poly all the way to the rads and it’s having a heat pump installed by another company.

This has me feeling really bad. 🤦🏻‍♂️

Thanks for the awesome info! I have a question, what do you mean by plastic pipes? You mean multi layer? And if so, why isn't this an option for heat pumps?

Can I use my gas usage to estimate the heating requirements for the house? Maybe the number of hours the heating was on for multiplied by it's power capacity?

Hi Adam, late to your channel. Could you do something specific to brands eg i have Mitsubishi ecodan and Mitsubishi recommend constant flow temp for under floor systems. I have tried weather compensation and it was terrible (cop 1.9) but i can squeeze 3.0 out at 7C ambient. I don't understand why that was the case and would love your take on it.

A great video , so you may nkt have to upgrade unfortunately to cut costs many homes built in recession times have very small pipes 10-15 even 8mm in at least part of the system to save costs, which is far smaller than any numbers quoted in this video .

i have the option of installing a buffer in parallel or in series (on the return) on a heatpump. what is best? With the buffer in parallel it does not need an additional pump

I use a gas boiler. If the government wants me to switch to a heat pump, they better be prepared to pay for the equipment and conversation. I won't buy something I do not want.

I connected my arotherm 105 monoblock with 32mm mlc. Heatloss calc at 8.9kw (design temp -7) so i’m a bit oversized on the heatpump. I’m debating wether i should fit in a volumizer/buffer in the return line to prevent cycling. What do you think?

I minimized use of couplings due to mlc so it cant be all bad i suppose. Have a run of 32mm mlc to the technical room of 6 meters from the arotherm to the belowfloors ufh manifold (hoh 10cm dst) and another 7 towards towards the first floor ufh manifold (in 26mm). Judging by the cheat sheet i should be fine.

Which heat meter are you guys using btw?

How would you integrate a 600l thermal store into a heat pump setup - as a giant buffer tank to take advantage of off peak electricity? Assuming a separate hot water tank.

So after watching all the info out there about heat pumps, I decided to go ahead. The good news is I would get a full installation for free paid by the UK tax payer because I am a pension and my gas boiler is LPG. The new installtion included 20 solar panels, whole house insulation and the heat pump with associated equipment, all provided and fitted free, not a penny for me to pay, yet would cost some 17k had I to pay for it.

So why did I not go ahead?

Microbore.

My house is a detached 4 bed and all rooms have radiators connected by 8mm microbore.

The assessment people did a survey and told me all my pipework would need upgrading to minimum 15mm which in turn means lifting every floor in every room to lay new pipework. This work would not be covered by the UK Government grants and I would be looking at around 10k to have them do all the work and make good afterwards.

I pointed out that some installers are saying microbore isn't an issue and they told me its all rubbish and these people don't know what they are talking about, further going into flow rates etc. as you have done.

So as a layman I am in a situation where I have no idea who to believe or where to turn.

A heat pump installation would cost me some 10K plus 17K = 27k to install, and at current annual savings even on LPG would take 67 years to pay for itself.

Its important when making these videos not to build peoples hopes becuase few will benefit from this technology without massive investiment.

Looks like its LPG for me.

The size of pipework has to be calculated. The starting point is the heat requirement of the system, then the operating conditions of the system ( usually determined by the temperature drop across the system which in most cases mean the required operating characteristics of the device providing the heating medium) Heat pumps operate at different system temperature drops than LTHW systems fed by a condensing gas boiler. OK, now you’ve established the system flow rate there are factors affecting the sizing of the pipework. High velocity in pipes is both noisy and energy hungry as it produces high specific pressure drops making the overall system pressure drop higher and consequently higher power requirement for the pump. So the size of pipework must reflect the types of pump that are economic for the application. Commercial projects require the same calculation procedure but may be less constrained by the above factors although it’s always sensible to optimise the capital and running costs of a system . Some older heating systems have larger pipework anyway ( ours has 35 mm common flow and return and the heating circuits start off with 28mm pipework). But the whole point if this is the need to calculate what you need rather than be guided by “rules of thumb” . Most heat pump systems that have been found to be inadequate are usually the result of poor design and installation as a result of not doing proper calculations in the first place.

how do you prevent short cycling when not using a buffer? turn-down ratio is high enough to not need one?

double the diameter increases the cross section area by 4.

Adam. Im so pleased you are talking 'Metric'.
Having been in Commercial HVAC for 51 years, we have been doing that since 1971, here.
Good job !

Hi, this is a general question about system design. I installed gas central heating and came up with a pipework design that didn't require any balancing of the emitters/radiators. It achieved this by having the flow and return run parallel to each other with the emitters bridging the gap. What's different about that you ask? Well as I can't draw a diagram here, just imagine folding your arms on your chest, then separate your arms slightly leaving a 2" gap.... that's the shape of my pipework, with emitters bridging the gap between the arms. The length of pipe that water has to travel is IDENTICAL FOR EVERY EMITTER, hence practically no balancing was required. I used 22mm for the biceps part of each "arm" and 15mm for the "forearm", so each emitter was either fed via 22 and returned via 15, or fed via 15mm and returned via 22. This meant flow resistance and total pipe length were near identical for all emitters. This is different to the standard approach, which has both arms held directly out in front, so that the emitters closer to the body (boiler) are fed through much shorter paths than the emitters out at the end of the arms. I think I used slightly more pipe than the standard approach, but it really wasn't significant. Are there any reasons why my design isn't the standard, or at least why it isn't offered as a practical alternative to the standard?

Would assume this is the internal area of the pipe not the OD of the pipe?

28mm pipework, load crap new build only

there is 1 caveat not considerd (properly): pumping losses. having bigger bores means your pump(s) have to work less hard wich means less pressure differential wich also means less cavitation in pumps and pipe noises and a big power saving. all in all its a win-win-win to have your pipes oversized. the cost difference is not much of a factor when doing a reno where you already are spending the cost of a nice car to upgrade the heating system.

What to do if one’s house is just 10 years old fitted with 10 mm plastic microbore pipes that feed all radiators from the first floor? That’s how so many modern houses are built by the majority of big developers.

Just found your channel and like it a lot. I'm about to renovate our heating system, and want to ugrade the ancient microbore piping and renew the radiators. What's the issue with 'plastic' pipe in heating systems ? There's very modern MLCP stuff like the Rehau RauTitan (not promoted much in the UK) which doesn't suffer the bore/flow restrictions at joints/fittings like some of the original 'pure plastic' systems I shan't name. Yes, you have to size the pipe correctly for heat delivery , just check the inner diameter !

Uhmmm, I am pretty sure that doubling the pipe diameter only gives you a factor of 4 in volume - unless you also double the length of your pipe! 🙂 Great video, though - you guys are really helping me prepare my plumbing for a future heat pump installation.

The cross sectional area of a pipe is irrelevant. The Hagen–Poiseuille Equation shows that with laminar flow, resistance to flow decreases with the 4th power of the radius. Double the radius, flow increases 16 times if pressure drop along pipe stays constant.

If you double the diameter whilst keeping the flow rate the same, then you quadruple your volume-per-minute - not octuple it.

well sheeettt my radiators are fed by plastic pipe, looks like heat pump will not be happening until i cant get the boiler fixed anymore

Is the delta T the temp drop across the radiator or is it the difference between the room temp and the average radiator temp? I'm sure I've seen it being used as both. If the heat pump runs at a temp drop across the radiator of 5 degrees what is flow temperature for most efficient running?

Anyone able to help me on this issue. If you have underfloor heating, where does the issue about pipe sizing end up? I suppose I may be looking at this arse-ways, but if the idea is to have pipes a particular size and the underfloor loop is narrower, does this cause problems?

Sadly a very large proportion of heating systems being currently fitted to new builds by the large developers use microbore plastic piping.. With the primary flow and return going up to an airing cupboard on the first floor and then separate 10mm F&R dropping down behind the drywall to the various radiators on the ground floor. This is the case in my 9 year old house, on top of that, not one of these new builds have heat pumps their all gas installations, so much for saving the planet!?

PS. Can you give the links to the cheat sheets you mentioned here - I couldn't see them on the screen.

Interesting video. If the flow and return connections on the heat pump are 22mm would you still recommend upsizing to 28mm for those primary runs to the hot water tank and the buffer? And when heating the hot water the connections to the coil are also 22mm.
Heat pump is 12.5kW.
Thanks for your advice.
John

You just rescued me with this video. I want a system, but style of recent videos cuffuddled my brain. e.g. Diakin expert. To give my statement context/goal posts, I am 72 with a degree in engineering i.e. OK with the maths, but swamped by the data flow! Because I am OCD, wanted to do number crunching myself AND compare answers with someone I trust before signing the cheque. Here lays the rub, Company A is modern, forward thinking but rushed off their feet with work and unlikely to have paid for your course. Company B is loyal but “back of a fag packet, we have always done it this way”. Thank you.

Great video as always keep up the good work.

Is there a video on using volumizers?

That’s the problem with so many new houses, like mine, from 2015… that they used 20mm copper pipe around boiler, water tank, etc…, but then the radiators pipe is flexible plastic 10mm pipe which is great/easier for them to install but not great for retrofitting…, and I guess a nightmare to change as will have to dig out holes in the whole house, lift floors, etc… 😩😩😩, so it may make my desire to install HP imposible. And so frustrating that all these thousands of new houses that you see around the country are being built have these pipes, well hidden within the walls, and with gas boilers…, and then thr Government want us to pay to change them to HP!! Bonkers!! 😡😡

Video appears to suggest Buffers are not generally required, however, has been suggested that most heat pumps require a buffer tank for defrost and to allow different temperatures in bedrooms compared to living rooms?

Would love to understand manifold distribution to individual radiators where pipe work to manifold is 28mm copper but radiators are 12mm plastic

Will this work for a heat pump?

4.58 2x diameter is not 8x the volume of water. is arround 6.5x de volume for the same headloss. the simplified formula is (internal diameter(biger pipe))/((internal diameter(smaler pipe))^2.7

example (25mm/12.5mm)^2.7 = 2^2.7 =6.498 about 6.5. this formula can have a max 5% error because of the different materials.

The calculation on diameter vs "volume" is wrong! The length is fixed, so the comparison is of cross-sectional area only which is obviously a square relationship rather than cubed. So doubling the diameter means the area/volume (for a fixed length of pipe) increases by a factor of 4 not 8! :)

Hi Adam, love the videos, but I think that doubling the diameter of a pipe would increase the volume by 4 not 8 as the length of the pipe would remain constant.

Question for your next episode as requested - what are you thoughts (pros/ cons) of the Octopus Heat Pump installations (equipment used and approach)?

Yes I'm interested. Has anyone written some FLOSS software (spreadsheet or other) for designing heat-pump systems? Overall demand, emitters, pressure drops, ground loop sizing, UFH spacing, pump power loss, etc. None of this is rocket science but I don't particularly want to do it all from scratch. Someone must have done this by now?

I've Just been looking at a brand new House that has an Air source heat pump but I noticed all the rads were fed by 10mm plastic pipe. It was a relatively large 4 bed house so would I be wrong in suspecting that the installers didn't know what they were doing?

Great video. The description still says coming soon for the article and cheat sheet. Any idea where I can find it?

I have plastic piping around the rads, does this mean it has to come out? Copper from boiler to pump thought.

So how about 8kw feeding 15mm old pipework running in and out of 22mm pipes?but mostly 15mm?