marshian

Yes to both The F&E tank is only feeding the CH Circuit - nothing is T'd off it - there is one isolation gate valve in the line but it's fully open The vent for the CH circuit is vented to above the F&E tank There is another vent from the HW cylinder that is vented to above the Cold Water Store Tank but there is no connection to it. The pump is installed the correct way round and as I thought the magnaclean filter has no flow markings and according to the destructions can be installed either way up The distance from the bottom T where the Vent is to the top of the pump gate valve is 58 cm it's as compact as it can be From the pump to bottom of the F&E tank is exactly 3.4 M The vent pipe is at it's highest point before it comes down to just above the surface of the header tank water is another 0.6 M Huge apologies to @Little Clanger for the threadjacking

Just looked at the instructions - not sure there is an orientation requirement on the Magnaclean but I will look carefully at the body when I'm home tonight

I'm not aware of an arrow in the filter body but I'll check that too Filter is checked every three months and rarely has much on it - below is as bad as it gets

Yes exactly that - 99.9% sure the pump body has an arrow pointing up but I'll check again

They are effectively stacked (with the absolute min of pipe between all items) Top Zone Valves Pipework Gate Valve Pump (130 mm flange to flange) Gate Valve Magnaclean Unit 22mm T (15mm inlet) Cold Feed 22mm equal T (22mm Vent Pipe) 22mm Flow from Boiler Bottom I can do exact measurements if required but it's all very tightly packaged

Ahh so one 22mm pipe feed from F & E to below the pump and then the vent tee's off close to the tank outlet - that would be do-able with existing pipework Attached is picture of set up before recent changes to pump filter configuration and valving

Glass of water results (might have to repeat it with a larger glass) pump on - level stable pump off - load of bubbles followed by a level drop pump on - all the water stolen from the glass Just for info when on HW both cold feed and vent pipes below the pump get hot for a few feet up the wall so there is a level of water in them When refilling the system from a drain down it fills fairly quickly so I think the cold feed is clear I would have expected the vent pipe to have water in it to the same level as the F&E tank

Yeah I’ll try the glass of water trick the filter is a magnaclean unit

Ok see below

Really good explanation and makes total sense My Pump is above the cold feed (so 2.0 M plus 3.0 M Head = 5.0 M) so there shouldn't be much chance of air being drawn in - I'll continue my search for why I get occasional slugs of air in the circuits I have turned the pump down from Speed 2 (3.0 M Head) to Speed 1 (1.8 M Head) to try and reduce the system noise and it all seems good on first pass (morning heating - selected rads)

Sorry to thread jack a smidge but thank you for that information - I've got a pump head of 3.0 m but the actual height of the F&E tank water level to the pump is closer to 2.0 m Might explain why I get occasional issues with air in the system with no apparent signs of leaks I think I'll see if I can drop the pump speed and maybe open up the flows thro a few rads to keep the circulation rate the same

Wow that's a heck of a flow rate for a shower - last time I checked ours when looking at water consumption it was 9L per min and I regard that as a decent shower I my concern for our house water usage I did fit a restrictor to reduce the flow to 6L per min and that was fine for me I couldn't notice the difference SWMBO who also didn't notice started whining that it was taking longer to rinse her hair (shampoo and conditioner) so the pump must be going and I should replace it asap................. I timed her showers with flow restrictor and without and it was a tiny reduction in water usage but it did increase the time in the shower by 50% and as I have to wait for her to finish in the shower before I can get in there I decided life was too damn short and I'd look for water savings elsewhere.

I thought that too

Is that the right way round and is it fully open? - stop cock is a fairly convoluted path for water - gate valve (fully open has very little resistance to flow - obv they get a little noisier as you shut them down)

I found using WIser Hub and Smart TRV's I have you could get one rad calling for heat setting the boiler off for a very reduced circuit and a shot while later another rad would call for heat - I think in one particularly cold night I burnt 23kW of gas for no appreciable increase in room temps overnight So I use it to schedule heating periods with a fairly aggressive set back temp at night (almost frost stat setting) this stops individual rads from calling for heat at night What I do like about the Wiser Smart TRV's is they do stay open for a really small trickle of flow and only shut down in the event of a considerable overshoot - so as I'm experimenting with a Weather Compensated flow temp it's actually helped me "tune" the flow thro individual rads especally at the weekend when I have the CH on all day

You have fridge and or freezer? - they randomly top up and cause a spike without you even noticing you are doing anything different. Difference from 0.15p per hour to 0.22p per hour based on say a 35p per kWh for electric is around 200W so it's not enough to be an immersion heater

^ what @Mike said - get a turbo nozzle for the jet wash lance - that makes short work of even the toughest lichen/moss/green

I had a concrete lorry as a garden ornament for a few hours - I'm sure I've got a picture - driver backed it into the garden to shoot a load of concrete into the footings - when it came to driving out he gave it all the beans and as a result dug himself a bit of a hole Ended up pulling it out with chains attached to another concrete lorry

That is a little poor (understatement) PS thanks for sharing the journey

In other news Gas Engineer has had it confirmed from Viessmann that boiler (in current configuration) needs a switched live from the programmer to the boiler - at bloody last!!!

Well my old school plan had a flaw - it wouldn't have been a problem if the gas engineer had used my 3 port valve as I proposed with no mid position in the old airing cupboard arrangement because I only had a bypass fitted for the CH side - HW didn't need one because the flow rate was always far higher (easiest path and all that) However now I have a bypass that will work if pressure in the system is high with CH or HW - closing the gate valve to increase the amount of time the water stays in the coil and reduce the return temp to the boiler is enough pressure to cause the bypass to want to play (By play I mean get involved) So tonight I've been experimenting with pump parameters to see if I can find a pump setting that Provides a min of 0.4 m3/Hr so that the boiler is happy with the level of flow (below 0.4 m3/hr the boiler gets a bit fussy and throws the odd "low flow" fault) when circuit is at it's smallest (ie just one or two rads in circuit) And provides a max of 750 - 800 l/hr (0.8 m3/hr) when all the rads are calling for heat so the boiler can ramp up and get the circuit up to temp Because the alternative plan is fit a NO zone valve in the bypass line so it closes at the same time as the CH NO zone valve........... Anyway no one wants to see a load of tables of what pump results in terms of watts, head and m3/hr is like for 3 different pump operating modes each with 3 different speed settings for both all rads calling for heat and a very tight circuit where I'm left with just two rads still calling (Bypass was closed for this) so I'll just say I've found a setting that meets the requirements but I haven't done HW on it yet.

First question - OK - there probably is an option to change temp or power on a Viessmann 4 pipe boiler but I don't have one of those - I have a two pipe "dumb" boiler with Viessmann "Extras" (actually calling it "dumb" is unfair it's really surprised me with just how clever the program in it is....... I think I've explained elsewhere reasons why I chose the 100-W heat only I couldn't fit a larger boiler in the space I have and hide it in a cupboard I didn't want to run another set of flow and return pipes for the system boiler Only the 100-W has flow and return exiting the boiler at the top (same as my old boiler) So I was pretty much picking what worked best for location and minimal changeover costs I've found a way to rein in the boiler modulation when doing HW, it's a bit old school but it's almost done the job (like everything it's a swings an roundabouts situation - or you could say actions have consequences but I've got a back up plan) Second Question - Temp wise it's 80 deg that's what the boiler targets I have the cyl stat set to 60 deg (it ends up at 63 on a friday legionaires cycle) and that's the only time the cyl stat actually gets to be in control - rest of the time - I have HW set to 20 mins on a timed slot - hence my end of HW temps can vary a little (anywhere between 46 and 54 depending on tank starting temp) but I can live with that. I always heat water before it's needed, I never have a HW demand at the same time as water heating I think the Cyl Stat hysteresis is quite wide - It's just a std Dayton HTS3 probably around 8 deg it also doesn't like being set below 50 deg as it doesn't have a positive off so it's really easy to think you've cracked a position for 45 deg and then find you have no HW because the next day it's Off I don't have an NTS sensor It's how I've always done HW always happy to hear alternatives to my current process but what I do works for us in the house. Sorry probably a bit wordy in reply!!!

So Viessmann Hot water demand box throws 80 deg C at the HW coil and ramps up to 100% Yes water reheat times are super quick but the boiler is quite noisy when it does HW and the tank only really can cope with 3-8 kW without the return temps being 10 deg less than the flow (Old boiler min was 10kW and that gave similar HW times to the viessmann when I ran it at 80 Deg C to get the water done without cycling) So if the boiler modulates based on return temps or flow (or both) Hello gate valve - happy to have you join the party - lets shut you down a little and see what happens 80 Deg C flow - boiler initially hit 100% but as I closed the valve it modulated down to 30% - 20 deg difference between flow and return (76 deg flow 56 deg return) - water heated from 20 deg to 52 deg in 22 mins It was a bit shunty to start with till I found a place where the boiler wasn't overshooting ramping down and then as the flow temp dropped too much throwing much higher kW at the circuit again Basically 1 turn open from closed seems to work fine - that'll do for starters

Gone old school and found a way forward to cap the boilers output - can't stop it going to 80 deg or trying to shove 20kW at the Hot Water circuit with the Demand Box parameters but I'll update that in my Viessmann Boiler thread.

Clarification if I wasn’t clear (I thought I was but apparently not) return pipe hotter than flow when the boiler is “off” I have probes on flow and return pipes after several hours of no boiler activity the temp in the return pipe above the boiler is higher thsn the flow - I believed this was down to thermo circulation - hot moving to cold the addition of s london loop has stopped it “dead”