jamesdiyer

Well 5. But the heat demand is very low currently. I'm not sure how to force the highest heat demand from the hestpump to see what the delta t and max kW produced is.

Actually looking the part manual they seem to be full bore and they're 1" so 22 internal but will know when off. If we're talking restrictions, then the plastic 25mm pipe fittings are internal of that. The pipe id is 20 and so you're looking at 15mm inside of the fitting id. But that's a very tiny distance, so I'm not sure it matters? (Everything matters in totality) Annoyingly vaillant Spain seem to be useless, which isn't good. I got some answers from vaillant UK very easily - flow should be targeted at 2000l/h, and send me their installer handbook with figures. Not surprising.

Good question. The red ones yes. The blue ones on the heating pipes should have come out during the install but we're left. They were only placed there so I could pressurise the system prior to installer coming to check some repairing I'd done was fine. So they'll come out when he's back.

Yes sadly that's so, and parts on the install weren't discussed with me. On another note, my monitor says basic circuit diagram 8. However if I am just with a volumiser and DHW tank, radiators only 1 circuit, should this be 7?

The sensor comfort is there temporarily, it's wired and I couldn't decide where to put it - walls are 80cm think. I'm running pure weather compensation. Yes your comment alludes to my first question, I felt 1700l/h is low - and I have a 15kw machine. But others here said running 32mm external 26mm internal plastic pipe over 11m isn't enough bore.

Another question. I noticed the flow return pipe between the 3way valve / volumiser and radiator input is done in 25mm plastic, so 20mm internal. It's about 3m of pipe overall. From A to B. After point B, the copper pipe splits immediately into two 22mm coppers one for upstairs on for down, so it is a restriction. The pipe between diverter is 32mm external. If on DHW cycle we get 2000l/h but 1700l/h heating circuit. Could this short stretch of reduced pipe be reducing flow so much? Before I ask installer to change.

The sensor is located near the heat pump in the shade but under a lean too roof, so it's a microclimate. I'll ask the installer to move it to a North wall. And thanks for confirming the tank situation, makes sense. It is actually a good location thinking about it, it's a 200L tank and some family members like scalding huge baths.

Also I realise I can reduce the target DHW temp. I should be less worried about temps as actual temps and treat them as a tool to adjust based on if we have enough hot water.

I do seem to have two issue. The exterior temperature sensor seems to have been placed in a microclimate as it's 2C above exterior (real) currently. Also the DHW is reading 23C as the sensor is quite low down, as on photo. Maybe this needs be higher. Or mains water arrives around 12C. The tank isn't 23C as it's coming out nice and hot. Suggestions on this one and where it should be would be helpful. I've set the DHW that it can heat in two windows per day (cheap off peak) so perhaps it's not an issue as it won't be constantly trying to heat. Thanks

Great thanks. Perhaps I'm making a deal out of nothing and we won't have any issue being warm with this flow. We will see, it'll turn real cold early November. But February is the worst as solar very low and all thermal mass gone.

.yes the fixings for plastic pipe are inside the pipe, versus copper which are outside, so each one has a greater effect on flow. It seems the k of that honeywell diverter is 8. So this might be something to look at changing. And check the filter as said. I'll wait and see how the system performs when it's really cold (cold here is -7C solid).

Okay thanks for the suggestion. This wouldn't have an effect on heating circuit or overall flow though no?

Sorry, I did say rough and I meant it. Good question. One tank is DHW, the other is a 100L volumiser, plumbed on the return leg to the ASHP, radiator pipe in at top of tank, exit to ashp at bottom. DHW right, volumizer left.

Running the hot water heating, we get 1900l/h. So loose only 200l/h though heating circuit. This is my rough circuit sketch of what I believe to be the index radiator, a point D.

No glycol, antifreeze valves.

I'm in Spain, but British. The 15kw isn't available in the UK, so I used the manual here. I believe it's the same hardware as the 12 but can just do more power. Maybe something wasn't clear by me. The pipe is 32 od but it's multicapa plastic so 26mm internal - this i what I thought I'd wrong and for a run of 11m should be larger. Thanks I'll check the filter.

I drew a plan and did some calcs. I stuck them in chatgpt, with a few prompts and we are both are 35kPa Inc +15% for fittings. Using flow of 1650l/h Can Simone explain delta T, which is assume is at the heat pump. Must it be 5C, or will it be ok at 7C? I'm struggling to find answers to these online. When I asked vaillant they said to aim for flow of 2050. My assumption was that the primary pipe makes a huge difference flow final flow, as it's 11m each way. Thanks

That's a good question. I don't know, as it's currently being installed. That's why I'm trying to understand now - if it's acceptable or not. Both before I pay the final bill, and before winter comes and when it's very cold we are not warm.

This is the 3 way diverter. Is the cv value the K? And this its 9.5?

Thanks for the pointers on things to look at, I will get on that. Is 11kPa pressure drop in the primary pipework really nothing? It's 1m head, which could be 0.4m head if it were 32mm internal? Or maybe I'm missing something? (We're talking about only the 22m total primary here, not the rest of the circuit). After the diverter the pipework immediately splits into two circuits of 22mm copper each, which tee off into 15mm tails of about 6 radiators on each circuit. Neither had too bit a head loss as a result of this immediate split flow. All lock shields wide open. Can I please check the location of delta t, and what flow rate I need? Here is pump curve. Number 3, VWL155/6

Hi all I've had a 15kw vaillant aerotherm plus installed. I'm getting a flow rate of 1700l/h, pump set to 100%. Volumiser of 100L, no buffer. Only machine pump. Manual says max flow is 2050l/h. I'm trying to determine if this is enough/acceptable. We have a heat loss off about 10kw at -7C. Unit does 12kw at -7. I understand heat = flow x delta t x 4.2 Is this delta t at the heat pump? The issue is, primary pipework was done in 26mm internal 22m total, and I'm frustrated by this, it's a 11.16 kPa loss v 4.2 kPa if in 32mm internal. Am I right in thinking if we had 32mm internal primary the flow rate would be higher and this we could carry more heat kW maximum for the same delta t? Is so what would the flow increase by? This isn't my area of expertise so I'm trying to get my head around it. Thanks in advance.

Hi all, I've had a few quotes in, the best one 15k eur is using Domusa Teknik machine (Spain based). The other quotes 22-24 are using Vaillant. Both are similar size Domusa duel clima 19 HT / Vaillant aerotherm 16 This is a significant difference in quote price. I know Vaillant are good, but it's hard to stomach that much more upfront. Does anyone have experiance of Domusa Teknik? https://www.domusateknik.com/en/dual-clima-ht#catalogue Thanks

Thanks good food to consider when specifying a ashp size, and good reason to not under spec. Yes, when I say backup, it could mean a 250l tank running separately for the loft annex or running in tandem with the main system. Night electric is cheap here so easy to heat up over night.

Spanish Pyrenees at 1000m. So cold like Scotland. Each floor is about 80m2. No gas to measure, we have a huge wood boiler, but running it at 50C keeps the house quite warm. I feel I modeled it quite accurately in heatpunk (I'm a civil engineer so not unfamiliar with it) and got 12k iirc. I said 14 give or take because I modeled at 18C everywhere and didn't include one currently unheated room in modeling, plus hadn't accounted for DHW if needing to.

Thanks. It's not 14kw with DHW. Currently got 250w immersion which would likely be kept as a backup and install a new tank linked with ASHP. Normally it's 2 adults and 1 kid but can go up to 5 adults and 4 kids if floor 3 annex is inhabited.