New beer - Found the forum to be a very useful resource

[marshian]

Hi All

 

Joined to comment on a thread I found whilst searching the interweb but seeing as an introduction is required thought I'd throw a bit of background down

 

Current house owned 33 years but updated over the years 1980's built detached 4 bed so originally open cavity walls, 25mm of loose fill loft insulation, single glazed doors and windows, void floor downstairs over a 2 - 3 ft crawl space and back in 1991 an annual gas usage for CH and HW of 25,000 kWh two floors with a total of 113 m2 (Small extension done in 2006 to building regs at the time) have reduced over the years with Double Gazing, Cavity wall insulation, upgraded loft insulation (could still be better), new boiler and replacement rads and spent 3 months last year doing 56m2 of 75mm PIR between the joists under the ground floor - amazing reduction to heat loss considering heat is supposed to rise 😉

 

Currently 8500 kWh gas usage per year for CH and HW but looking to use it more effectively rather than reduce it further 

[Big Jimbo]

Welcome, it's a great place to be. Enjoy.

[Sparrowhawk]

Welcome @marshian, that's an impressive reduction in gas usage you've managed!

 

On 02/10/2023 at 22:40, marshian said:

and spent 3 months last year doing 56m2 of 75mm PIR between the joists under the ground floor - amazing reduction to heat loss considering heat is supposed to rise 😉

 

I'd like to know more about this as when I modelled insulating our suspended wood floors it reduced the heating demand by less than 10% - nearer 5% IIRC.  Do you think the reduction in heat loss you saw was from the insulation or from improving airtightness and reducing losses due to draughts through the floor?

 

[marshian]

11 hours ago, Sparrowhawk said:

Welcome @marshian, that's an impressive reduction in gas usage you've managed!

 

 

I'd like to know more about this as when I modelled insulating our suspended wood floors it reduced the heating demand by less than 10% - nearer 5% IIRC.  Do you think the reduction in heat loss you saw was from the insulation or from improving airtightness and reducing losses due to draughts through the floor?

 

 

Combination of both - reduction in heat loss and improved air tightness - the lounge used to be a drafty place - giveaway was black edges to the carpet next to the skirting so it took a fair bit of heating (it's slightly compromised by only having one very big rad for a fairly large room) The airflow under the house is quite a high rate when the wind blows with one air brick every five bricks outside (house was built near a flood plain and the water table is quite high)

 

Of course actions have consequences and one I didn't expect was I had to fit a PIV unit in the house to get humidity levels under control because the lack of drafts meant that occupants created humidity increases that weren't offset by air ingress.

 

Room temp used to target 21 now it's comfortable in the 18/19 area

 

Two rooms have tiled floors which in previous winters would be bloody cold now they are cool in winter but not freezing

 

Hallway and dining room are oak floor over the original chipboard even those floors as I was insulating has improved surface temps.

 

The insulation combined with a few rad upgrades enabled me to get the boiler into condensing mode more often - previously in winter we had to set it to 75 deg flow (so only condensing on part of the warm up phase) not really taking advantage of the condensing eff benefits at all

 

The weeks that were minus temps outside we ran at 68 - rest of the winter 64/65 was fine and I was able to drop it to 60 in the spring.

 

For this autumn/winter/spring I'm targeting 45/55/45 respectively (depending on outside temps) as the remaining T11 rads have now been replaced with T22 or vertical ones

 

The other contributor may be fitting Wiser controls and Smart TRV's but last winter I ran it like an on/off timer rather than a 24/7 with setbacks due to issues I had with heating controls (old sunvic wiring centre with relays) - I think I'll use a little more gas with 24/7 and setbacks but the house will feel nicer as a result.

 

The biggest issue I have with running lower flow temps is water heating - I have a heat only boiler with no facility to set different temps for water heating - I have to do this manually by raising the flow temp for 15 mins of water heating and then dropping it down again for the CH - this quite frankly is a PITA and I'd like to find a way out of this faff.

 

At 55 deg flows I can run HW and CH for a long time and get a high 40's tank temp at 45 deg flow temp I just get a tank full of water at just under 40

[ProDave]

Hi and welcome to the forum.

 

Cutting your heating usage to 1/3 what it was originally is very good, and shows what can be done to older houses.

 

If you wanted to get better hot water performance while keeping to a lower boiler flow temperature, you might look at changing your hot water cylinder for a "Heat Pump" version.  These have a very much larger surface area input coil for better heat transfer.

 

I have one (heated by a heat pump)  the maximum flow temperature of my heat pump is set to 55 degrees.  My sweet spot is DHW set at a tank temperature of 48 degrees.  That is hot enough to get almost uncomfortably hot water for the kitchen sink and washing up and plenty for everything else.

 

Some of the boffins on here would be pulling their boiler apart, fitting a second thermostat and a relay to switch between them to give different temperatures.

[marshian]

4 minutes ago, ProDave said:

Hi and welcome to the forum.

 

Cutting your heating usage to 1/3 what it was originally is very good, and shows what can be done to older houses.

 

If you wanted to get better hot water performance while keeping to a lower boiler flow temperature, you might look at changing your hot water cylinder for a "Heat Pump" version.  These have a very much larger surface area input coil for better heat transfer.

 

I have one (heated by a heat pump)  the maximum flow temperature of my heat pump is set to 55 degrees.  My sweet spot is DHW set at a tank temperature of 48 degrees.  That is hot enough to get almost uncomfortably hot water for the kitchen sink and washing up and plenty for everything else.

 

Some of the boffins on here would be pulling their boiler apart, fitting a second thermostat and a relay to switch between them to give different temperatures.

In reality I'd reduced it to 16,500 before last winter so 1/2 the previous year usage but still a huge reduction.

 

Annoyingly I replaced the vented HW tank a few years ago (old one needed 1 hr to heat water due to scale inside - hard water area) so it's not that old but I'm sure you are right if I could get a better vented HW tank with a high surface area coil it would probably help a lot when at lower flow temps (at the same time I fitted a water softener so I'm not expecting the same level of scale build up impacting water heating performance)

 

Re-boffins activity - yeah but I'm not a boffin and any of that is probably beyond me.

[SteamyTea]

On 02/10/2023 at 22:40, marshian said:

Current house owned 33 years

My much smaller place is 35 years old.

Doing the same as you, small insulation improvements and better airtightness, along with much better DHW management, means I now regularly use a third of the energy I used to, last year was almost a quarter.

Daily monitoring helps.

Going to be interesting as I now work days again, instead of evenings, that may push the usage up.

[marshian]

4 hours ago, SteamyTea said:

My much smaller place is 35 years old.

Doing the same as you, small insulation improvements and better airtightness, along with much better DHW management, means I now regularly use a third of the energy I used to, last year was almost a quarter.

Daily monitoring helps.

Going to be interesting as I now work days again, instead of evenings, that may push the usage up.

 

Imagine if everyone improved their insulation where possible/practical set their boilers up to be more efficient and minimised wasteful running - how much energy could be reduced across the country???

 

Don't start me off on daily monitoring as it's become a bit of an obsession 🙂 (Having said that coming from a manufacturing background we always say "what gets measured always improves")

[SteamyTea]

7 hours ago, marshian said:

how much energy could be reduced across the country

If there are 30 million homes, and they use a mean of 15 MWh/year, then reducing that by a third would save 150 TWh/year.

The UK, in 2019 used 1651 TWh of energy.  So around 9% of our primary energy. Would be a little better than that as homes used delivered energy.

 

 

[marshian]

might as well sling this here

 

My return temps are still too high IMO even at 52 deg flow temps

 

Add to this one of the new vertical rads isn’t heating up very well

 

The en-suite one warms two vertical bars up before the warm water returns via the other six vertical bars

Flow temp in 44.0 deg and return is 35.2 so nearly a 10 deg drop

 

The bathroom one (identical to the en-suite) just seems to heat the bottom of the rad and the flow and returns are nearly identical.

So I thought I’ve clearly dropped a clanger and fitted it upside down so the flow is short circuiting the rad (there is a blank in the bottom rail that stops this happening)

 

I drained that rad and took it off the wall - shone a torch in the bottom and the blank was at the bottom so I hadn’t fitted it wrong. I was confused and I’m still not sure what made me do it but I looked thro it with a torch on at the other end - this is what I saw

 

https://thumbsnap.com/s/Dgccj4CJ.jpg

 

And from the other end

 

https://thumbsnap.com/s/muHuRPpG.jpg

 

That’ll be a gap round half the blank leading to a short circuit - raised the issue with the supplier as I’m pretty sure that’s the issue with poor heat output and very little difference between flow and return. If I up the flow temp to 70 the rad heats up well but I think thats just a consequence of heat rising much faster at higher temps.

 

Either way I think I’ve found one reason for my higher than expected return temps

 

The other reason was my own fault one rad had been left with the trv body set to six when I thought I’d set it to two.

 

Left the bathroom rad off and isolated - fixed my error on the rad with the wrong setting and hey presto knocked 3 degrees off my return temps compared to earlier in the day when I was checking flow and returns to tweak a few rads that were heating up rooms faster than others

Edited October 29, 2023 by marshian

[marshian]

Well the supplier initially offered £30 "compensation" and I could keep the Rad that short circuits - I rejected it and they came back with £50 "compensation" & Keep the rad - I asked at what point they were going to get to agree to replace the rad or refund me completely as that was the only thing that was going to resolve the issue.

 

Replacement arrived yesterday - I've looked in the inlet and shone a torch thro it and there are just 4 pin pricks of light visible so this one should perform as good as the other one which gives a good drop between flow and return and heats up well

 

Not sure what to do with the defective rad but I did find this on the web for £30 ish

 

https://www.bestheating.com/milano-flow-diverter-15mm-inlet-chrome-63476

 

I reckon if I knock out the blank completely it would fix the issue and I can use the rad in another room (this was my back up plan if the supplier didn't replace it)

 

In other news following reading posts on here by @JohnMo I've been looking at Buffer Tanks to see if I can help to alleviate my Boiler oversize issue

 

TL:DR - Can a HW Tank act as a buffer in when the HW coil is in circuit with the CH

Well I've had a bit of a break through but I've thought I've got this damn boiler and heating system sorted before and I haven't but this time I really think I've cracked it.

Flow temp 55
Return when TRV's start shutting down is up to 40
Pump speed still on speed 2
ACT (anti cycle time) still 35 (so 14 mins ish at 55 Deg Flow)
PO (Pump Over-run) Still 6 mins
RR (Range rated) 14 kW

Running 55 deg flow temps is fine at the start of a heating period when all rads are calling for heat. I get a nice long heat up burn, rooms warm up and there are no issues but as rooms get up to temp and the TRV's start shutting down the boiler has to wait for 14 mins (ish) due to the ACT setting between burns.

If I shorten the ACT parameter the CH circuit is still too hot when the boiler fires it overshoots in under a min.

With the ACT set to 35 it gives a decent length of time for the flow temps to drop into the mid 30's so I get a longer burn (2 mins) but it's still not long enough to heat the circuit....

Result is the few rooms still needing heat just don't ever reach target temp as 2 min of heat into the CH circuit isn't enough to make a difference at the rads

I really need about 4 to 5 mins of burn for the CH system to get the rad temp up into the mid 40's where it starts to make a difference to room temp.

If I drop the pump speed to 1 it makes the burn cycle shorter still so that's not an option

If I increase the pump speed to 3 it makes the system incredibly noisy when just one or two rads are in circuit (it's a bit noisy on pump speed 2 but I can live with it)

In summary with a 10kW min output from the boiler and a house that is not leaking heat at a fast rate I'm a bit screwed because until more rooms call for heat the last remaining rooms don't actually get any warmer (they don't lose heat admittedly but Mrs BC says they aren't warm).

So as above I've been reading up on buffer tanks - they are just an insulated tank with a volume that can be put in the heating circuit to increase the system vol (when rad TRV's shut down and reduce the size of the circuit)

I haven't got one but I have got a HW tank (Well a heating coil in a HW tank which adds a bit of volume)

Now I know heat transfer is a lot slower at lower temps (ideal way to heat water is high flow temp - large differential - quick heat up) but if I close the gate valve to give somewhere for the excess pressure to go to as the TRV's start shutting down the HW tank coil and circuit can act as a bit of a buffer. Hell it can't hurt

So last night I tried it for two hours 3 rads calling for heat plus HW with restricted flow (13% open) system was quieter initially I thought it was a bust as the HW circuit stole a lot more heat than expected but as the tank came up to low 40's it worked much better. HW tank ended at 44 deg.

Watching the tank temps (I have probes top and bottom) when the boiler was firing the bottom tank temp went up - when it wasn't firing the temp bottom temp went down - overall the top of the tank was gaining temp over the period.

The 3 rads in circuit were a lot warmer (I think they were stealing heat from the tank)

There was less system noise

Return temp at the boiler ranged between 36 and 42

It seemed like a plan so I left the set up like that for this morning - I lose about 0.5 Deg an hour from the tank overnight as long as I don't over heat it.

House warmed up fine 0620 hrs to 0745 hrs (so 85 mins of CH and HW combined) - Tank temp got to 46 Deg in that time and I used a little less gas than previous morning (where first HW ran for 30 mins at 72 Deg Flow to get to 48 Deg and then CH ran for 60 mins at 55 Dec Flow) but that was probably down to having the tank heated the previous night.

This evening was going to be the test (OK today was a little milder and we got a little solar gain in some south facing rooms) but to be fairer I extended the evening CH cycle by an hour

So 1630 to 1700 Just CH because all rads would be calling for heat for first 30 mins
From 1700 to 2000 it was CH and HW together with same gate valve 13% open configuration

House felt much warmer went we walked thro the door at 1800

Gas usage From 0620 to 1800

Yesterday 31 kW
Today 23.7 kW

Gas Usage from 1800 to 2000

Yesterday 12.4 kW
Today 4.4 kW

Last 1hr boiler activity when CH system only had 2 Rads in circuit - I think best I've got down to before was 3 Rads

4.5 Min Boiler On
13.0 Min Boiler Off (Pump On)
3.5 Min Boiler On
14.0 Min Boiler Off (Pump On
5 Min Boiler On
14.5 Min Boiler Off (Pump On)
4.0 Min Boiler On

So roughly 17mins of boiler firing and 41 mins of pump running not firing (4 cycles per hour) and during that hour it used 1.7 kW of gas

Return temp never went above 40 Deg

HW tank temp went from 40 Deg to 45.5 Deg so not overheating the water but that's a temp I'm perfectly comfortable with.

It will lose some overnight as we normally only heat the water once a day but it will reduce the load on the system in the morning when it's a shorter window so it's a loss I can live with.

I'm going to see how it goes but it seems promising...........