Gordo

That is the problem. Statutory bodies only spot check work, developers and contractors and architects all profit (survival) driven. Time is money so lets cut that down to the bone. the only way to get some quality is to self build, arm yourself with knowledge (google) and supervise everything personally. Not a task to be taken on lightly and with a monumental learning curve with no dry runs. Obviously all this quality will come at a proportionate cost or time penalty.

Ohhh the general industry's understanding of thermal dynamics in a dwelling is virtually zero. beyond some professor or such. Thermal comfort is I believe much more complex than just degrees. I do know that humidity and air movement are significant factors which are usually ignored. Also heat loss calculations really only look at heat conduction again radiation and convection are generally ignored. for example the muli layered foil insulation products cant get any traction in the market because the cant prove the real world performance claims based on current testing procedures. Only conductivity performance figures are used based on a BS "hot box" test rig.

Modern houses and their heat losses could be better predicted but the house building system in the uk with speculative developers offering minimum supervision over sub-contractors working to a bottom line and minimal statutory oversight doesn’t bode well for the actual houses performing to design assumptions.Developers have only a passing intrest in the ongoing running costs to the owner of the dwelling. I would like the industry to provide thermal imaging or such to buyers along with a AI report based on images on the predicted heat losses. the as built SAP calculations which output the EPC certificate should be a good indicator of heat loss, but for the above reasons and inaccurate as built input data are often way off.

I work in the technical side of building. I can confirm that there is understanding out there. Few apply their knowledge in their specialty as it as it takes time and time being money which few are willing to pay for.

I agree it’s the science / understanding that underlies it becoming obsessive trying to fine tune something to be as efficient as possible

I’m afraid I’m a bit of an obsessive tinkerer. Slightly concerned that a HP install could end up as another obsession that I spend disproportionate amounts of time playing with 😂 but I do have a small wood stove that I adore. So don’t really want to give it up completely. Want the HP to provide a background heat to say 19 or 20 degrees and walk the stove on on colder evenings. Thinking internal temperature sensor for HP would be advantageous?

Oh that’s new to me “load compensation”. I’m familiar with “homely”. So some HP don’t take internal temperature into account just outside with weather compensation. How do we find out which HPs don’t look at internal temperature? Look at controller data sheet maybe. do you think that “load compensation” is something I should want, or can WC generally take care of it when set up properly

thanks guys that advice was helpful. so most HP have a fixed flow rate. HP all vary flow temperature based on how far off from the set target flow temperature weather compensation will auto adjust target flow temperature based on inside/outside temperatures based on some selected algorithm (graph)? think i got it.

Octupus not available im my area 😞 I only get 7hrs E7 at 14p. Export at 10p so i try to consume myself before exporting. Iwill do a cost benifit calculation to see if HX is worth it. But my gut says not

wow that post is i litttle over my head. it sounds like you opted to replace the DHWC in the end for a HP cylinder? I think my existing cylinder should work but would have to fit a booster pump to increase the heat transfer, or fit a plate heat exchanger. Im thinking id be best to just stick with the immersion heater on PV or E7 tarrif.

hi i'm designing my HP system in preparation for the "professionals" design. Heatpunk design comes out at 5kw heat pump @ 45 degrees for an annual heat load of just over 11,000 kwh for space heating. My historical heating works out at 12,500 kwh, with a pellet boiler and includes DHW and some supplementary heating with a small log stove. Therefore im pretty content with validity of the heatpunk design output. its a reasonably well insulated 2003 house about 180m2 floor area what im intrested to know is how the heat pump modulates its output. I assume the flow rate is fixed? do heat pumps modulate the flow temperature up / down or is that generally set (fixed) at the controller. then it just modulates the input electric to maintain the set flow temperature until it can go no lower and shuts down for a period (cycling) unassuming the flow temperature is set (fixed) at controller is it a matter of playing with controller to come on the minimum flow temperature needed. how does weather compensation come into the equation. will this then adjust the flow temperature automatically. probably silly questions for those in the know. lol Thanks in anticipation

do you mean a 1m2 primary heating coil? with a pump to increase the flow through coil? what l/m pump did you decide on

intresting. not much more Kw than my own

Any feedback on how it performs would be appreciated

the boiler is only about 10 years old. it has quite some life left in it yet. I hear grant will be coming in next year or two so just planning a head. I didnt want to over size the pump as the average temperature is around 7 degrees. dont know much about frosting up, so ill have to research that end. Does an oversized ASHP frost up less?

yes N. Ireland. i have historical data for past few years which show it rarely goes below 0. So if i have the option i will design for 0 degrees, but suspect MCS engineer would refuse to do that. MCS state design for -1.5 degrees for Belfast. in the few days it goes below 0 degrees im happy to fire up the stove.

would you mind looking at your data label on UDHWC and let me know the Kw rating of primary heating coil for comparison.

I hear you and agree if tank was old id replace. but at £1500 the payback would be unrealistic. Heating with immersion works out at around £255 PA. if the heat pump managed a COP of say 2.5 id save say £102 PA with a payback of over 15 years if i replaced tank. I guess what Im wondering is if a 5Kwh heat pump could heat my existing tank with its 16Kw coil? I assume the 16Kw is based on a flow temp of say 60 degrees. Most HPs can manage 60 degrees but probably not with a good COP. Maybe im ignorant but id assume 5Kwh DHW load with 16Kw coil at 60 degrees would give theoretical a heat recovery in the region of 30 minutes now. From experience that bears out now. But if i fit a 5Kwh heat pump that obviously changes. Surley the heat power from HP would be say 2.5Kwh maybe at 60 degrees (maybe this is silly thinking and it remains at 5Kwh with more electric consumption). This would mean a reheat time of say 2 hours at 2.5Kwh (or 1hr at 5kwh) at around 60 degrees. I assume the HP reduces the flow rate automatically to achieve the set 60 degrees. maybe iv got it all wrong. help i need educating

I am considering a ASHP to replace my pellet boiler. I have done space heating heat loss calculations that indicate a peak load of 4.7Kwh at -1.5 degrees outside. So aiming at at 5Kwh heat pump. I have a pretty new 200l UDHWC with a 16kw / 0.7m2 primary heating coil which i am reluctant to dump. if using the pellet boiler to heat it i have to close off gate valve to tank to almost closed because the DHW demand is so great. I generally heat tank with immersion heater at night on E7 or with solar in summer and use about 2-6Kwh per night as it works out cheaper. I think i would be a loooooong time payback on new HP tank so would prefer to keep my tank and heat it with the HP. Has anyone got any advice for me please?

The first plan of stair with landing tapered would comply with B Regs. Maybe not so pretty tho. The 1/4 landing mentioned by someone would have a single step at top which wouldn't comply.

Fixed price all the way. Time and materials contract will spiral out of control fast. Unless you can financially incentivise the project manager to meet targets. say basic weekly wage for PM and then a bonus for meeting targets like meeting cost, time and quality targets. I don’t know how you would set such targets without professional advice from a QS. Be very careful not to allow contractor/PM to load payments towards the early payment. I have seen some horror stories Where PM has been given too much scope basically stealing materials and defrauding his client. Don't do it unless you are actively involved and very careful and remain suspicious/vigilant

Don’t do it like this. It would be a bodge job. The company’s who upgrade conservatory roof have had structural engineers advice and from experience have to load test the completed roof to measure deflection in window frames to get BC approval. even then I don’t like it. Often the foundations and floors are substandard. I’d suggest tumble it and start again as safest route.

I agree. Grout it. The small crevices will hold water and you will have lime scale and mould even if your substrate isn’t soaking. Not worth the risk

Oh ? I thought he mentioned SIP panels roof under EPDM and your last post here discussed a warm roof. In that case and it’s a cold deck roof ignore all I said ? But advice stands if it’s a wam deck roof.

How long is piece of string? Cost depends a lot on where you are located and how high your specifications are. Knocking it down and disposal won’t be the main cost it’s the rebuild. Any budget cost I would quote you are likely to be irrelevant.