Micro-bore Pipework & Heat Pumps: How To Make It Work. 

Thanks for the video - I'm 2 weeks into new ownership of a heat pump with 10mm microbore. A buffer tank was installed with the wilo pump set similar to in your video. I was worried given the amount of negativity about buffer tanks that are on YT and the various heat pump communities that it was a mistake, but you've made me feel a lot happier now!

Great video with good information helping to dispel myths and lack of knowledge. Doing the basics; heat loss, index circuit and flow calcs is vital for edge systems like this, but as you point out should be standard practise on all system design.

Excellent job, just shows it's critical that those calculations are done correctly. Thanks for sharing/

This is another really useful video. I especially like the introduction to flow rates, pipe sizes and index circuits. Which I am very families with as I used those parameters a lot when designing commercial and very large domestic systems. I think that the requirement to understand and apply this design process is going to become increasingly important in the domestic market and this will present a steep learning curve for many domestic installers. I would always use a buffer store when installing a heat pump to an existing microbore system. They operate in a similar way to a low loss header. I only ever use Grundfos pumps😊

My home has 10mm plastic microbore drops down, 15'mm copper 1st, with a 7kw Daikin monoblock installed over three years ago on a gov trial. SCOP for heating and DHW is 3.15 consistently annually, but DHW alone is about 2.3 and in cold months heating is 3.5, so not bad. The installer put a 20 litre volumiser in to increase the volume. Flow is about 19 litres per minute, heat loss 4.3 kw. The living room radiator is at The end of The run and does struggle to warm up, so what you are saying runs true. But overall the ground floor microbore hasn't been tragic for our set up

Really interesting. I have 10mm micro bore (copper) to all rads (4 bed detached), uninsulated concrete ground floor slab & insulated cavity walls. I've been holding back on a Heat Pump for a few reasons. Micro bore pipework, outdoor space issues for HP & my current boiler is only 5 years old. At least the Microbore issue can probably be discounted now leaving just the other two issues to be overcome. Was thinking about Air to Air with a separate solution for HW but now leaning towards a Monobloc ATW or perhaps even a split ATW. Lack of BUS for ATA will probably rule it out.

I wish i had your knowledge on these kind of things. Great video

Outstanding, I really need to speak to you about doing a survey on my house for a heat pump

Excellent Syzmon, you are knocking these out of the park now.👍 Did you OE monitor this install?

Design is clearly everything, and there few like you who have the required skill set. I live in a 1994 build 4-bed detached house with 8 mm copper microbore and original oil-fired boiler, burning through 1,100 litres/yr (+ wood-burning stove with free wood in a semi-rural location, so smoke pollution isn't an issue). It works very well, and I wouldn't even dream of changing this set-up until the boiler finally dies, because I could so easily end up with a cold house from a mis-designed system.

Probably quite lucky that the existing system was designed on 11k dT. I would have expected the usual 20k dT. Ive got the same issue, with grey plastic microbore all over. Doing my calcs has suggested i need a separate circulator so going with larger pipework to/from the Heat Pump and a low loss header. That gets me a reasonable amount of volume into the system and also hydraulic seperation. Fingers crossed!

Excellent educational video. How do you go about matching the flow rates on both sides. As in the ciculator in the outdoor unit modulates up and down based on demand and the indooor one you have wont? Have you ever thought of buying the same circulator that the outdoor unit has and using that as the post buffer circulator and then using the same pwm control that the outdoor unit uses to also control the pwm on the post buffer circulator?

Hi! Great video! I was wondering about piping of a buffer tank - I thought installing buffer tank as hydraulic separator hurts systems efficiency... Is this 3-pipe return buffer piping better than other piping arrangements and do you you always use it when installing buffer as hydraulic separator?

What insulation have you used in the airing cupboard ? Looks great. Having experimented with my own system it’s very clear flow is king with a Heat Pump if you can get better than required cop will improve.

I have no idea on the flow rate! A bad set of fittings, or where they used a couple of unnecessary elbows where a sweeping bend would have worked, would make a huge difference. The turbulence caused by fittings can represent many meters of straight lamina flow through a pipe. It might be worth mapping the circuit with a borescope through small test holes in the ceiling to inspect cross joist junctions. If you find any culprits, you could swap out a few bad sections - as a few access holes, in the plaster board, aren't that hard to patch up especially if you know where the joist are, and you could save the costs and space of the second pump/buffer. I'm a big fan of fitting the largest cylinders possible, because they act as thermal batteries ready for higher RE grids with super low/free off-peak tariffs. There's a lot we could do to increase the packing factor of storage volume in mechanical spaces. The other question is whether the effect of the volumizer/buffer could be replicated with larger volume rads - at the end of the day, that would give you the thermal inertia you need too, as well as more surface area. Edit:yup, mapping the system for future leaks is also a nice bonus!

Are all units that you install mono block? I didn't see any split units, or at least refrigerant fill ups

Thanks

Szymon, is the neutral point at the buffer now or is that an issue with heat pumps higher flow rate?

Did you consider using a bypass gate valve between the primary flow and primary return to allow some of the 800l/h required by the heat pump to be routed directly to the return, reducing the flow round the microbore to, say, 600 l/h with 200 l/h going straight to the return and then being mixed back with the radiator return. The delta on the rads would then be more like 7K but mix back to 5K with the bypassed flow added. I’m planning to try this approach on an upcoming install. I like the approach because it simpler and requires less kit and space. Do you think it will work ok?

I've yet to transition to an ASHP and presently running a boiler. All the drops to the ground floor radiators are behind plasterboard in 10mm microbore (15mm in the ceiling before each drop). I've done my own heat loss spreadsheet - it's a complex building (1990 build, but not a simple rectangular box) - which seems to correlate reasonably well with my worst case daily gas use. I've compiled a map of my radiator plumbing detailing the pipe gauges and all the Tees, but I've not estimated the lengths of each segment. How necessary is this step? I believe the index circuit can be identified without.

I would have left buffer in, as we don’t have x-ray eyes with an old system very difficult to get all the dirt out and people need to consider reliability. It will reflect badly on your system if it’s constantly erroring. This will be the bread and butter job in the next 10 years.

When you turned off the gate valve to the buffer did that remove the resistance of the secondary pump? If you had of removed the pump and put a straight through pipe, would that have removed enough resistance to then run it without the buffer?

If I fit much larger radiators can I run on a gas boiler at at very low kw out oug puts .

What make is the phone please and which brand was the insulation thanks

Thanks for the video, I have a question on the increased flow rates when switching from gas to heat pump. If the gas boiler is already running at 35'40'C DT5 and keeping the house warm, with 10mm plastic does that mean a heat pump can/will also work without buffers etc?

I really love what you do but in this particular case, condens boiler with new rads would be better option. Looking that hot press packed is worst nightmare for any technician and any repairs in future.

Without the buffer in this system the HP would begin to ice up quite a bit and reduce eff% of the actual HP . Yes/no ?

Could you also have plumbed the secondary pump in series with the internal one in the heat pump (i.e. as a booster)? In my mind the heads of the two pumps would add together and the flow would increase. Is there some problem with this - the heat pump control loop fights against the external pump or something? Or is the buffer just the neater install?

Thanks for this video. I have microbore but 10mm copper attached to 22mm with heat loss of 8.5kW. Would you typically expect a buffer or additional circulation pump to be required like in this video installation?

What if you increased flow temp a little to compensate for a smaller rad?

Any thoughts on 8mm copper pipework?

@ 10:20 - it will not get weaker with time … it will only fail … it is an electronic pump with monitoring… The old pumps have running capacitors for the motors - if the capacitor value degrades the motor will run at lower speed …. But in electronic pumps if there is something wrong it will show an error or it will totally fail …😊

Will the system be noisy with a larger pump and small pipework ?

I love these guesses - 600

I'd put 22mm copper with short 15mm bits to the radiators

@ 9:40 In this case I never replace the whole pump ; only the motor and I keep the pump body on the pipe if they are the same brand of pumps from the same family…😊

What was designed flow temperature?

860 L/hr is bang on 5KW. The heat pump would never exceed that on central heating?

Thanks

Hmmm what I would do ? I would use Tado, and switch of the rooms that I don't use, rather than running all the house at full tilt all the time .... still cheaper than a heatpump installation cost + electricity used.

Just looking for 1) How much a heat pump would cost over 10 years including the gas/electric/servicing cost in the UK. 2) How much a gas boiler would cost over 10 years including the gas/electric/servicing cost in the UK. I can work it out for the gas boiler but just get if's and but's from heat pump sales people.

Prediction from 7m34s: It'll work! Maximum flow 700 litres/hour.

11:03

780l/h my guess

The chances of an Irish installer knowing this sort of thing is about 1/40.

Nice work 🙂