Secondary return or trace heating tape?

Chickereeeee

Thanks for replies. 

Don't forget, with secondary return you have to recover the heat lost from the primary feed and the return pipe. So maybe twice as much as electric heating of primary only.

fenwick458

I had a similar problem in my house, the combi is getting old (15years?) and is never really fast to generate hot water at the kitchen sink at the best of times, but sometimes it seems to fire up, just as the water is getting warm after 1 minute it'd go stone cold for 1 minute, then start burning gas again and heat it up. Maybe someone could offer a diagnosis of it? used to do it rarely, maybe 10% of the time but it was really annoying and it seems like such a waste having to run off all that water
anyway, my solution was to install an instant hot water tap in the kitchen, I got a Qettle and that seems to have solved the problem for now. according to this review , and adjusting for todays prices it costs just over 6p per day to run it in standby mode
the 90W trace heater would be in the region of 70p per day

Bendy_House

Chickie has an unvented cylinder, I understand.

On that point, Chick, is your mains pressure good - 3+ bar? Do you even have a PRV on it to reduce it to ~3bar?!

Anyhoo, the run length you are talking about is only around 10m? For the little outlay - ~£25 - I'd test Grumb's idea to the next level, and buy a 10m coil of 8mm copper microbore pipe to test this in reality.

Chickereeeee

Bendy_House said:

Chickie has an unvented cylinder, I understand.

On that point, Chick, is your mains pressure good - 3+ bar? Do you even have a PRV on it to reduce it to ~3bar?!

Anyhoo, the run length you are talking about is only around 10m? For the little outlay - ~£25 - I'd test Grumb's idea to the next level, and buy a 10m coil of 8mm copper microbore pipe to test this in reality.

Yes and yes, to your questions. 
I'll mention  it to plumber, although not sure how simple it would be to replace existing pipework. Maybe during next litchen refurb.
 On the same loop (probably) is the downstairs toilet and the hot-fill dish washer.

Chickereeeee

fenwick458 said:

I had a similar problem in my house, the combi is getting old (15years?) and is never really fast to generate hot water at the kitchen sink at the best of times, but sometimes it seems to fire up, just as the water is getting warm after 1 minute it'd go stone cold for 1 minute, then start burning gas again and heat it up. Maybe someone could offer a diagnosis of it? used to do it rarely, maybe 10% of the time but it was really annoying and it seems like such a waste having to run off all that water
anyway, my solution was to install an instant hot water tap in the kitchen, I got a Qettle and that seems to have solved the problem for now. according to this review , and adjusting for todays prices it costs just over 6p per day to run it in standby mode
the 90W trace heater would be in the region of 70p per day

Re the hot tap idea: I have only really seen taps that do boiling water (and cold filtered)', in addition to normal hot/cold feed. I.e. they can replace a kettle. For most kitchen purposes, you want hot, but not boiling water, and these don't seem to offer that.

Bendy_House

10m run at 3bar+ pressure - I wouldn't anticipate any issues at all, for any of these items.

I suspect Grumb has cracked it. You 'may' notice a fluctuation if another tap is used at the same time, but it should be of little consequence.

One issue... Your plumber may not recognise this as a credible solution - it might depend on how old school they are Folk like Grumb - who aren't actual plumbers - have garnered their knowledge independently, and understand what can work, especially if thinking outside t'box.

Section62

Bendy_House said:

One issue... Your plumber may not recognise this as a credible solution - it might depend on how old school they are Folk like Grumb - who aren't actual plumbers - have garnered their knowledge independently, and understand what can work, especially if thinking outside t'box.

Folk like grumbler won't be called back to redo the job when the client finds out that it doesn't work as expected - whereas a professional plumber risks not being paid, or taken to court by the client for their 'defective' work.

I would use 10mm plastic though, not 8mm copper.  The plastic will help slightly with reducing heat loss.

grumbler

Section62 said:

Bendy_House said:

One issue... Your plumber may not recognise this as a credible solution - it might depend on how old school they are Folk like Grumb - who aren't actual plumbers - have garnered their knowledge independently, and understand what can work, especially if thinking outside t'box.

Folk like grumbler won't be called back to redo the job when the client finds out that it doesn't work as expected

Really? I will and I don't have any problems with this.

With regard to the 'old school', do you know how many plumbers stubbornly dress thread of compression joints? Thinking isn't their strong part, let alone thinking outside the box.

Section62

grumbler said:

Section62 said:

Bendy_House said:

One issue... Your plumber may not recognise this as a credible solution - it might depend on how old school they are Folk like Grumb - who aren't actual plumbers - have garnered their knowledge independently, and understand what can work, especially if thinking outside t'box.

Folk like grumbler won't be called back to redo the job when the client finds out that it doesn't work as expected

Really? I will and I don't have any problems with this.

With regard to the 'old school', do you know how many plumbers stubbornly dress thread of compression joints? Thinking isn't their strong part, let alone thinking outside the box.

I'll rephrase -

"Folk like grumbler cannot be legally compelled to redo the job at their own cost or pay compensation when the client finds out that it doesn't work as expected"

grumbler

Well, my informal obligations are probably more valuable than 'legal' ones that pretty often are very difficult or even impossible to enforce.